Ren Krawler is a Gundalian from Bakugan: Gundalian Invaders. He is a protagonist in Super Smash Bros. Crossover and, along with Nurzak and his team, helped create Battle Gear for Tiggrera and Preyas. His Guardian Bakugan is Linehalt and his Battle Gear is Boomix. Ren takes off his disguise for the first time during Jesse's funeral. In Season 8, Ren is entrusted with one of the keys to Pandemonium. Ren, Fabia, Sonic, and Zombie Spider-Man later try to save Goku, but arrive too late. Ren then pursues Venus after she retreats. Eventually, he fights Venus, as well as a brainwashed Fabia, at Brinstar Depths. Despite getting assistance from Peach and Ness, Ren is defeated, losing his key to Pandemonium. Ren, Peach, and Ness are now under Xaos' control. Ren is freed after Naruto transfers some of his energy into him. After defeating Xaos, Ren is embedded with the core of Pandemonium. In Season 9, Ren made the Smash World Grand Prix open source, allowing more people to compete, but also making it vunerable to hacking. After losing to Anubias, Ren loses the remaining control he has over the tournament, but regains it at the midway point. From that point onward, Ren is training to control his new powers. Prior to the final battle with Mag Mel, Ren is transported to another dimension and is forced to face illusions of past foes. Eventually, Ren and the others realize they made the same mistake Master Hand made by not trusting their friends. As a result, Ren finally regains control of his powers. Afterwards, the Heroes of Legend return to Earth to help their friends. During the finale, Ren finally settles the score with Anubias. Ren and Fabia then head to the Ivory Towers to help the other Heroes of Legend in the final battle against Mag Mel. Ren returns to Gundalia at the end of Season 11. In Season 12, Ren is ambushed by Yami Bakura, who retreats after telling him he captured his teammates. Ren pursues him to Earth and encounters Zelda, who Yami Bakura had corrupted after sealing a fragment of his soul within her Triforce of Wisdom. In Season 13, Ren fights Fabia in an attempt to bring her back to her senses, but is defeated and his essence is returned to the Smash core. Ren is revived at the end of Season 13. In Season 14, Ren is unwillingly sacrificed to boost Pandoria's power. Ren is revived at the end of Season 14. In Season 16, Ren is notably the only Hero of Legend, other than Fabia, who doesn't go to Pandemonium during Gigadark Bowser's invasion due to the fact that Gundalia could be targeted next. Ren reappears in Season 20 to help in the struggle with the Akatsuki. During the finale, Ren and the other Heroes of Legend fuse with Naruto in order to help him defeat and purify Samus Aran. After the battle, Ren is restored on the Space Colony Ark. In Season 22, Ren develops hatred towards Meta Knight after the psychopath kills his teammates. This eventually causes Ren to become a Dark Hero of Legend, becoming an antagonist as a result. Ren is later released from his hatred, but allows himself to be arrested due to his actions. Later, Ren and Sonic are forced to defect from the Heroes of Legend after being blackmailed by Zelda. Ren later abandons Zelda and attempts to redeem himself in the eyes of his friends. Later, Ren and the other Heroes of Legend, except Anubias and Sellon, sacrifice themselves to stop Samus' self-destruct from blowing the Earth apart. Ren is later revived when Bowser forces the Offspring of Zorc out of the Millennium Ring, which the Heroes of Legend had at the time. In Season 24, Ren goes to Neathia with Bowser, Pichu, and Sakura Haruno in order to stop Fabia from turning the Neathians into cannibals, but is killed by Mechtavius Destroyer shortly after Linehalt. Ren is later revived due to Drago killing Mechtavius Destroyer in the past. In Season 29, Ren is emotionally damaged after Coredegon releases a zombie outbreak upon Gundalia, and is later infected during the Grand Finale in a failed effort to help Fabia Sheen prevent Neathia from suffering the same fate. Later, Ren is successfully cured by Batman while he is distracted by an alternate version of Ben Tennyson that is merely the Ultimatrix when untransformed.
Ren's first appearance is based off of his outfit he wore in his disguise before joining the Castle Knights. His second outfit is based off his Mechtanium Surge appearance.
Ren's personality is unchanged from Gundalian Invaders. He shows a lot of concern for his team, shown when he was worried about Zenet after Zombie Reed pierced her, and tried attacking Peach and Zelda of the silly Melee universe after they burned Mason. In Season 9, Ren was much more violent, especially with Anubias. In Season 10, Ren is devastated about Zenet and Lena going rogue. When Mason too gets corrupted, Ren is even more violent than he was in Season 9 to the point where he brutally massacres Zombie Reed out of pure rage.