Note: Some of this information may be taken from other interpretations, but this is information of how I think the characters of Smallville turned out. Some feedback could benecesary, as well.
Clark Luthor: When he arrived in the 1989 meteor shower, young Kal-El was found in a cornfield by Lionel Luthor. Lionel raised his super-powered son along with his real children, Lex and Lutessa Luthor. While turning his back on Lex, Lionel favored Clark as his best heir and raised him to become a domineering tyrant. Being a super-powered being, Clark, after being convinced by Lionel, turned his back on Jor-El and adopted his Ultraman persona, becoming a mass murder and claiming countless lives, including Lex's, Virgil Swann's, and Patricia Swann's, while also being the owner of all of Metropolis and the LuthorCorp Media. Eventually, Clark departed his earth and went to a world where he is a force for good, while his counterpart, Clark Kent, took his place. When Luthor returned to his world, he killed his longtime rival, Oliver Queen, for revealing his secret and weakness to the locals, who all started carrying meteor rocks around with them to protect themselves from Ultraman. Once again, Clark escaped to Earth-1 and trapped Kent in his world while he himself took Kent's place. During this stay, Clark stalked his alternate sister, Tess, and forced her to be on his side to help him kill Lionel, who had been on Earth-1 for some time. After Tess betrayed him, Clark attempted to kill her, but was stopped by Kent, who convinced him to go home and repent for his past actions. Having a new lease on life, a redeemed Clark return to his world. Unfortunately, the locals rejected Clark for his past evil actions, causing him to return to evil and wipe out most of Metropolis in a rage. Therefore, Ultraman seized abosolute control over his world, being more evil than ever, until he was stopped by Kara Zor-El/Power Girl, whom he released from suspended animation when he destroyed the Reeves Dam during his rage against the world that rejected him.
Lionel Luthor: Lionel is a domineering and munipulative tycoon whose life was similiar to that of Earth-1 Lionel until he found young Kal-El in a cornfield and raised him as his son, along with his biological children, Lex and Lutessa. In favor of his Kryptonian son, Lionel turned his back on his real son and even allowed Clark to kill him. Lionel and his only remaining son took control over Metropolis and Lionel helped Clark create the Ultraman persona to keep the Luthor name unharmed. Lionel even went as far as deactivating Clark's biological father, Jor-El, after Clark had united three stones together to create the fortress. Eventually, his son was transported to a parallel world and Lionel was visited by an alternate version of his son. This was when Lionel regretted his decision to allow his son to kill Lex and when he return to Earth-1 with Clark Kent without the latter noticing him, Lionel took control of Luthorcorp from Tess and attempted to get Lex back, using a clone of his deceased to join his side. LX-15, reformed into the good Conner Kent, turned his back on Lionel and then Tess took Luthcorp back from Lionel. After this, Lionel descended into madness and went to the greatest lengths to get Lex back. He was even willing to carve out his daughter's heart to give to a Lex clone, but this plan failed when she escaped and shot the mad tyrant, who then consequently sold his soul to Darkseid, secessfully resurrecting Lex for good, although Lionel died after this.
Alexander "Lex" Luthor: Lex was the son of Lionel Luthor that was betrayed, due to Lionel favoring his super-powered son. Lex held a grudge against his brother ever since Clark, as a young child, threw a temper tantrum that killed their mother, Lillian, in the process. Escaping the Luthor curse, Lex, now preferring to go by his full first name "Alexander", went on to college and lived a normal middle-class life. He met a Smallville girl named Lana Lang, whom he eventually married and together had a child named Alex. Later in life, Lana was pregnant again with their upcoming daughter named Lilly, but before little Lilly was conceived, Clark Luthor killed poor pregnant Lana and young Alex to get back at his rival brother, Lex. Since this incident, Lex was more determined than ever to bringing his domineering brother down and started experimenting with various types of meteor rocks to find his brother's weakness. This was when Lex used the gold meteor rock to brand an "L" on Clark's forearm. As a result and with Lionel's approval, Clark incinerated Lex with his heat vision killed him without any remorse.
Lutessa Lena Luthor: Lutessa was the only daughter of three children from Lionel and Lillian Luthor. Her brother's names are Clark and Lex. Growing up, Lutessa had a sexual relationship with her brother Clark, unaware that he slept with multiple women in his bed. Also, Lutessa had a resentment toward Lionel, paralleled to the resentment that Earth-1 Lex had toward his father. Both Clark and Lutessa planned to escape to Earth-1 to start a life their, without their father being in the picture. However, Lutessa briefly met an alternate good version of her brother from a parallel universe and when Clark Luthor returned to Earth-2, he continued his relationship with Lutessa and later went back to Earth-1 to try and start a relationship with the other Tess, due to being the most hated and feared person in his world.
Lana Lang-Luthor: Lana's life was similar to that of her Earth-1 doppelganger, as she still attended Smallville High School and dated Whitney Fordman, although she never developed a friendship with Chloe Sullivan and Pete Ross. Her parents were still killed in the meteor shower when poor Lana was 3 and she still was raised by her Aunt Nell. Sometime after graduating from high school, she met Alexander Luthor, whom she married and had a child with named Alexander Jr. Consequently, Lana was pregnant with her and Alexander's second child named Lilly, who was never conceived due to Lana's brother-in-law killing her and little Alex to get back at Lex.
Lois Lane-Queen: This Lois' relationship with Oliver Queen advanced to the point that the two eventually became engaged and married. She worked at the Luthorcorp Media with Clark Luthor being her boss. When Clark as Ultraman killed her husband, she held a stronger grudge against the mass murderer, but she already hated Ultraman in the first place when he killed her cousin. At her husband funeral, she saw Clark and used Kryptonite against him, not knowing this was not Ultraman but Clark Kent from Earth-1, but she became convinced and allowed Kent to escape. Later on, Lois was one of many people who rejected the seemingly redeemed Ultraman for his past actions and ended up killed with most of Metropolis.
Oliver Queen: Oliver was a billionaire who failed to become the hero he was supposed to be. Ever since they attended prep school together, Oliver had a rivalry with Clark Luthor, but was good friends with Lex, who was eventully killed by Clark. Oliver also had a sexual relationship with Lois Lane and became engaged with her. Ever since Ultraman killed Dr. Virgil Swann and his daughter, Oliver had been hunting the mass murderer down and finally came face-to-face with him when Kent from Earth-1 came to this world. As soon as Oliver realized this was a good Clark from another world, he let Kent go and later revealed Ultraman's secret and weakness to the locals, who started carrying meteor rocks around to protect themselves. For this, Clark killed Oliver in the similiar manner he had killed Lex. Chloe Sullivan and Pete Ross: Chloe and Pete both attended Smallville High School and graduated in class of 2005. In this world, both of them had a sexual relationship and eventaully got engaged then married. However, Chloe stumbled upon Ultraman's secret identity and when she schemed to write an article and expose his secret to the world, she fell victim to Clark, who killed her, along with her husband Pete, who already had held a grudge against Clark for being a Luthor.
Jonathan and Martha Kent: Jonathan and Martha were happily married prior to the meteor shower, which caused both of them misery. They both separted when Jonathan became an obsessive, angry, and bitter man who lived alone on the abandoned farm. Due to this, Martha couldn't bear to stay with her husband. Eventually, Jonathan captured and held Clark captive, not realizing this was a good version of the guy from another world. When Kent convinced him he was not Ultraman, Jonathan let him go and after being convinced by his would-be son, he visited Martha and the couple reconciled.
Davis Bloome/Doomsday: Davis, along with Clark, was found by Lionel Luthor, who immediately pitted them against each other to figure out which one was the traveler. As it turned out, Clark was far more advanced than Davis in his abilities and managed to upper hand and kill Davis before he could gain his healing factor.
Genevieve and Jason Teague: Both mother and son were obsessed with finding three mythical stones. In this world, Jason never had a realtionship with Lana Lang. He and his mother eventually got their hands on one of the stones, but ended up killed by Clark Luthor, who took the stones and united it with the others.
Whitney Fordman: This Whiteny's life is exactly the same as the Earth-1 Whitney, with the exception of Clark Kent's influence. He still had a relationship with Lana, went to war, and got killed in combat.
Henry James Olsen: Jimmy never had a sexual relationship with Chloe in this world, although he was great friends with her and Pete. But he did work at the Luthorcorp Media, stumble upon Ultraman's identity, and end up becoming another victim of the mass murderer.
Kara Zor-El: Kara was released from suspended animation when Clark Luthor/Ultraman damaged the Reeves Dam during his furious rage against Metropolis from when the world rejected him for his past actions when he tried to redeem himself and become a hero. Not being able to find young Kal-El in this world, Kara gave up that task and decided to become the Metropolis' own superheroine, first being known as Good Samamritan, The Blur, and finally Power Girl, whose archenemy was Ultraman. Eventually, with a scientist's (this world's Emil Hamilton) help, Power Girl was able to defeat Luthor when Hamilton bulit a machine that allowed one to travel to other dimensions. Emil sent Kara to Earth-1, where she seeked help from Clark Kent/Superman and the rest of the Justice League, who all came back to Earth-2 with Kara and eventually defeated Ultraman.
Zod: General Zod always remained in the Phantom Zone and was never released, as there was no second meteor shower and Brainiac never made it to Earth. As for the clone, the orb has never been found and used in this world, so Major Zod and all the Kandorians remained within it