As far as a complete restart of the DCEU
1- Man of Steel (1st film of the DCEU; love interest Lois Lane; villain Zod)
Begins with an agent from the Department Of Extranormal Operations visiting Kent Farm in Kansas days after Kal-El appears. Pa Kent convinces the agents to allow him to keep baby Kal-El but the agents say that if Clark's secret gets out, they are coming to take him away. Cue montage of important events in the first 29 years of Clark's life including him finding out about his origins, building the Fortress Of Solitude, talking with AI Jor-El, creating the Superman suit, saving people, and moving to Metropolis to work in the Daily Planet.
Enter Kryptonian terrorist Zod who escaped being imprisoned in the Phantom Zone and fled Krypton just hours before its destruction. Zod appeared on Earth when Kal-El was a baby and was imprisoned in Area 51 by the United States government. He escapes the base and sets out with the goal of freeing his army from the Phantom Zone and conquering the world to create a new Krypton. But first, he must kill Kal-El, his primary obstacle in this goal.
At the end of the movie, Superman, with the help of DEO agent John Jones uses the Phantom Zone Projector to imprison Zod after a battle in the Appalachian mountains.
The post-credits scene is a man in a penthouse, watching Superman speak before the United Nations. You dont see any of his features, but you can tell he is wearing a suit. A female voice says Mr. Luthor, Lucius Fox is here to see you about that agreement with WayneTech, and Lex gets up and leaves.
2- The Batman (2nd film of the DCEU; villains Joker & Harley Quinn)
Begins with a clip of a news station talking about a mysterious vigilante known as The Batman. Zooms out to reveal a grid of other clips of people talking about the Batman, along with blurry cellphone footage of the Bat in action. Eventually, the grip is panned out completely to reveal that the massive grid of clips is in the shape of a bat symbol. Suddenly, cut to Batman and Dick Grayson as Robin stopping the Joker for the first time ever.
Cut to four years later, and Jason Todd is the new Robin, and Batman has a new ally, Batgirl. Meanwhile, the Joker gains a new therapist in Arkham Asylum named Harleen Quinzel, who he subtly manipulates over the course of weeks until she falls completely in love with him. She breaks him out under the new persona of Harley Quinn.
Joker meets with Scarecrow, who agrees to develop chemicals for him. He makes his escape known by heading to the home of Commissioner Gordon, ringing the doorbell, and shooting the person who answers. That person just happens to be Barbara Gordon. He then begins his massive crime spree. The movie shows various scenes of Joker and Harley causing chaos throughout the movie
Batman initiates the search for Joker, with Barbara helping him from her hospital room. He and Robin track down and defeat Scarecrow, but Batman is hit with fear gas, forcing Robin to defeat Scarecrow on his own. Back at the Batcave, Robin says that since he defeated Scarecrow, he should be more independent. Despite being advised not to by Batman, Robin sneaks out in the middle of the night, only to be captured by the Joker. Batman tracks Robin down to a warehouse, but just when he arrives at the warehouse, a bomb detonates.
Batman eventually finds Joker at the Gotham reservoir, where he first met him, but gets into a fight with Harley. During the fight, Batman tries to help Harley realize that Joker does not really love her. This eventually leaves Harley in absolute tears, allowing Batman to run and hunt the Joker.
Joker tries to get Batman to kill him by saying all the bad stuff he's done in the two weeks he's escaped Arkham. Batman explains that his job is to bring people to justice and let the court decide what to do with them. Joker brings out an assortment of thugs to fight Batman and escapes. After taking out the thugs, Batman looks for Joker, only to find him incapacitated by Harley, who is holding a gun to his head. Batman convinces Harley to spare Joker and turn herself in. The final shots of the film before the credits is Batman watching as Harley carries Joker's unconscious body out of the reservoir, surrounded by GCPD, as you hear his internal monologue talking about how his parents taught him that no matter what a person does, no one deserves to die. The post-credits scene is Batman calling out Supermans name. Superman flies down, saying that he does not have a lot of time to talk. Batman says that hes been watching Superman and others like him for a while, and that at some point, they are going to have to form a team.
3- Wonder Woman (3rd film of the DCEU; love interest Steve Trevor; villain Cheetah)
Begins with a scene of Hippolyta explaining that thousands of years ago, the Greek Gods created the island of Themyscira for the Amazons where they could live alone, without the influence of men. As they couldn't reproduce, Zeus provided their queen, Hippolyta, the ability to create new Amazons from clay, along with the souls of woman who died disgraced by men. Since the Clay Amazons had vague memories of their past lives, they held great contempt for men. Hippolyta decided to keep Themyscira isolated from the world.
In the present day, Diana is the heir to Hippolyta's throne if and when she dies. Diana is widely loved and respected by the other Amazons. One day however, an American Air Force pilot named Steve Trevor crash lands on the island, and Diana hides him from the Amazons, knowing that they would most likely kill him if they found out he was on the island.
Hippolyta finds out however, and to Diana and Steve's surprise, she is perfectly fine with it. Hippolyta explains that she has had her eye on Man's World for a long time, and she feels like Themyscira should join the outside world. Not only does Diana become Themyscira's new ambassador, she also has the duty of protecting Man's World from threats, both political and supernatural. The media calls her Wonder Woman.
A large chunk of Amazons are not happy with this decision, believing that Themyscira must stay isolated. One of them is Priscilla, an Amazonian military leader, who rallies an army to march on the Themysciran capital to kill Hippolyta and take control. She also dons a magical cheetah pelt, turning into a woman-cheetah hybrid.
Diana teams up with the US Military to protect the capital and defeat the rebel army. The film ends with Diana being given a medal. The post-credits scene is Priscilla, nicknamed "The Cheetah" by the media, imprisoned in Stryker's island, a prison in Metropolis for criminals and terrorists with extraordinary abilities created after Zod attacked.
4- Superman 2: The Man of Tomorrow (4th film of the DCEU; love interest Lois Lane; villain Brainiac; Supergirl appearance)
The movie begins with scenes of Krypton's destruction described by Jor-El's AI in the first film. An alien hive mind named Vril Dox is "bottling" the most major cities, before destroying the rest. Inside the city of Argo is Zor-El, Jor-El's brother, who is sending his teenage daughter, Kara Zor-El, to Earth to guard over her baby cousin Kal-El.
Clark Kent is living happily with Lois Lane in his apartment, serving as Superman on the side. He is asked to perform an interview with billionaire Lex Luthor. He learns that despite Lex celebrating Superman on the news, he secretly despises him and only pretends to like Superman for PR. Clark can't publish this however, since Lexcorp's media division owns the Daily Planet.
Lex is later shown touring Area 51 for new technology, where he sees a broken robot that crash landed on Earth in 1958. The robot was one of Vril Dox's drones, but was disconnected from the hive mind before it crashed. Due to it's vast intergalactic knowledge contained in it's storage, the workers have nicknamed the robot "Brainiac". Lex heads home with access to Brainiac's database, as well as a Phantom Zone projector. He briefly brings out Zod under red son lamps, takes away his translator ring, and kills him with two shots to the chest with revolver. Now able to understand the database, he researches Kryptonians, and discovers that the irradiated pieces of the planet Krypton have harmful effects on them when under a yellow sun. He starts recreating these pieces, branding it "Kryptonite".
Meanwhile, Kara Zor-el finally arrives on Earth, decades too late. She meets up with Kal-El, and explains who she is. The two cousins bond over the course of the movie, saving people as Superman and Supergirl. However, this is cut short when Brainiac arrives, working with Lex. Thinking that Brainiac is bluffing, Lex allows him to bubble cities, one of which is Metropolis. Brainiac announces to the world that they have three days before the chosen cities are miniaturized and the rest of the world is destroyed. A scientist named Hank Henshaw volunteers to team up with Superman and Supergirl to stop Brainiac. He is wounded and completely paralyzed in the process.
In the climax of the movie, Lex discovers Brainiac's true nature to destroy the world, and attempts to stop him. When Superman shows up however, Lex decides to fight him instead. Supergirl confronts Brainiac Prime, the central body of the hive mind, in his ships. Brainiac pins Supergirl down, forcing her to watch as he destroys the remaining Kryptonian cities one by one. Just before he can get to Kandor, Supergirl manages to free herself and crushes Brainiac Prime's skull. This all happens while Superman apprehends Lex in his warsuit, but he manages to escape.
After Brainiac is defeated, Lex becomes the FBIs Most Wanted and goes into hiding, Supergirl lives on Kent Farm, and all of LexCorp's assets are bought out by numerous companies, including Wayne Enterprises and Queen Industries. The final moments of the film show Lex, in rage at losing his company at reputation, shaving his head to disguise himself, his hatred for Superman only increased. The post credits scene is Lex in the Slaughter Swamp of Gotham city, looking for pieces of Brainiac technology. He sees the massive head of one of Brainiac's ships buried, resembling the headquarters of the Legion of Doom from the Super Friends cartoon.
5- The Flash (5th film of the DCEU; love interest Iris West; villain Reverse Flash)
Barry Allen as a child saw a strange man in a bright yellow suit murder his mom and frame his dad for the murder. Years later, he is now a forensic scientist at the Central City Police Department. One day, he hears that his father was murdered in prison and no one knows which other inmate did it. While working the graveyard shift one night he sees a yellow light encircling him and he falls unconscious.
When he awakes, he discovers that he can now move at incredibly high speeds. He develops a superhero persona called the Flash, based on a hero with similar powers in the 1940s. Barry tracks down this old superhero, and discovers that he is Jay Garrick, a very old man in a retirement home. The two talk about their powers, and they discover that the circumstances in which they got them were extraordinarily similar. Jay also explains that the man he saw was Reverse-Flash, Jays arch-nemesis. Jay explains that Reverse Flash was a criminal from the future named Eobard Thawne who apparently tried to recreate the event that gave Jay his powers.
Reverse Flash gathers a team of Central Citys worst super criminals to oppose Flash. This group is called the Rogues, and consists of Captain Cold, Weather Wizard, Mirror Master, The Trickster, and Captain Boomerang. After foiling a massive bank heist by the Rogues, with Captain Cold being the only one who escape, the Flash is honored by the city. The post-credits scene is Captain Cold walking into his hideout, where he finds Lex Luthor waiting for him, accompanied with several Brainiac robots. When he tries to fire his Freeze Ray at Lex, one of the robots speeds forward and grabs the Freeze Rays. Lex explains that he did not mean to startle Cold, he just has an offer for him.
6- Aquaman (6th film of the DCEU; love interest Mera; villain Black Manta)
Arthur Curry, also known as Orin, is a human-Atlantean hybrid and the king of Atlantis. He was the child of a fisherman named Tom Curry and Atlanna, the former queen of Atlantis.
After what appears to be a terrorist attack on the Royal Palace, an investigation commences. Garth, the grandchild of Royal Advisor Nuidis Vulko, is one of the few survivors of the bombing and wishes to help Orin find the terrorist responsible
Orin discovers that the perpetrator was the Black Manta, a mysterious masked criminal who arrived in Atlantis from the surface world, longing to live with them. He has an incredible hate for Aquaman, and wishes for nothing but his death.
Black Manta is imprisoned in Strykers Island after a long, tedious battle between the Atlantean army and Black Mantas forces, The Neo-Atlanteans. Orin than makes the decision to reveal the existence of Atlantis to the world, taking cues from Themyscira. The post-credits scene is Black Manta sitting in his cell without his suit, when he sees some people walking by. Some are DEO agents, while some are Strykers Island guards. They seem to be transporting what looks like some kind of giant starfish-like creature with all kinds of machinery hooked up to it.
7- Green Lantern (7th film of the DCEU; love interest Carol Ferris; villain Sinestro)
Hal Jordan is a test pilot who wished to become an astronaut, but was rejected. While walking through the woods, he is suddenly teleported to a dying alien named Abin Sur, a member of the Green Lantern Corps. Hal is enlisted, the first human to do so since the 1940s..
Hals first mission is to attack a member of the Sinestro Corps led by Thaal-Sur, Abin Surs brother who is more well-known as Sinestro. He is accompanied by Kilowog, his alien partner. On Earth, he is assisted by John Jones, who seems to have not aged since we saw him in Man of Steel.
Hal eventually discovers that a massive army of Yellow Lanterns led by Sinestro is heading for Oa. A massive battle occurs, and the Green Lanterns win. Sinestro escapes and heads to Earth to get payback against Hal for defeating him. Green Lantern defeats him in a battle in the Earths Atmosphere, and he is imprisoned on Strykers Island, and has the ring confiscated. The post-credits scene is a man watching footage of Green Lantern fighting Sinestro. The camera slowly pans, until it reveals John Jones. A silhouetted figure smoking a cigar comes in and informs John that something crashed near the small Rhode Island fishing town of Happy Harbor, and that he needs to investigate.
8- Justice League (8th film of the DCEU; Phase 1 Complete)
The film begins at Strykers island, where Captain Cold, along with an assortment of Lexs Brainiac drones, are attacking Strykers Island, intending to break out its inmates, who are all the living main villains from all the previous films. Superman arrives, but is surprised when Batman arrives as well. Batman explains that these drones busted into Arkham as well, and he wants to know how these drones are still active. Batman is also working with the DEO, especially John Jones, who has shown incredible detective skills.
Superman and Batman round-up the heroes who defeated the villains, and form the Justice League, based on a similar organization called the Justice Society in the 1940s, which the original Flash and Green Lantern served in. Meanwhile, the first meeting of the Legion of Doom, a group of super criminals dedicated to take down Superman, is called to order. Lex explains that the starfish creature he found in Strykers Island has the ability to give birth to smaller parasitic versions of itself. These parasites essentially latch themselves onto the hosts face and take psychic control of them. Lex plans to have one control Superman, turning him into a tool to help him conquer the world.
While talking about the Justice Society, John Jones reveals that he is actually the Martian Manhunter, one of the original members. He says that he wishes to join the team, as the Justice Society was the closest thing hes had to a family since he lost his old one on his homeworld of Mars, and he longs to be a part of something like that again.
The Justice Leagues first mission is to investigate strange activity in Happy Harbor. While there, they meet a teenage boy named Lucas Snapper Carr who says that the rest of the town is being held hostage by Brainiac drones. The team split up to free everyone and defeat the drones.
While all of this is happening, the Legion of Doom secretly ambush Superman, and latch one of the parasites to his face. While he is completely under the Starfishs control, Superman receives visions. He learns that this being is called Starro The Conqueror, and that it has infected thousands of planets before, and once it breaks free from the Legions control, it will do so with Earth.
Before the group can release the signal, Superman comes in, completely under control of the Legion of Doom. He almost manages to kill Batman, but the rest of the team subdues him. As Green Lantern and Wonder Woman hold him in place, Flash starts the machine, killing all of the parasites. Superman tells the team what he learned while under control, and they head towards the Batcave to try and locate where Starro is kept.
As a last resort, Lex attempts to create a clone of Superman, using genetic material he found on the black market. However, the material is unstable, so he uses some of Zods blood as a catalyst. What is created is Bizarro, as nicknamed by Captain Cold. However, the clone turns out to be very kind and sweet, so Lex has a parasite attached to him. Strangely, since Bizarro is flawed, he is controlled by what remains of Starros consciousness, rather than the Legion itself. Bizarro rips the device out of Starro and it regains full control, bursting out of the Hall of Doom. It escapes into the high atmosphere, creating millions of Starro Parasites that spread all over the world. Starro then escapes into outer space,
After learning of this, Batman contacts the Daily Planet with the intention of sending a message. Superman begins to speak on behalf of the Justice League to millions of viewers around the globe and he deliers a speech, asking superheroes around the world to help fight Starro and protect people who have not been affected by him. As he is speaking, brief cameos of various superheroes suiting up are shown.
Scenes of superheroes around the world fighting Starro-Infected around the world are interspliced with scenes in the Batcave, where Batman and Flash are working on a device that would increase Martian Manhunters strength 10,000 times. They plan to release a worldwide psychic wave that would destroy all of the parasites, which they manage to do. After this, all the Legion members are all incarcerated once again, including Lex and Bizarro this time, who are kept in solitary confinement. Meanwhile, the League receives a commemoration at the Cincinnati Museum Center, the original meeting place of the Justice Society. Superman initiates a speech announcing Justice League International, an official union of superheroes across the globe. The post-credits scene is Starro in some kind of restraining device, surrounded by aliens monitoring his progress. A man in robes is speaking to a shadowy figure about finding Starro floating in space, and that he has information on the last Kryptonian. Pan over to the right slowly, revealing Darkseid, whose red eyes lighten up as he grins evilly.
As a massive Hawkgirl fan I would have absolutely no problem watching that 
