Stomps his way through all of them save the last two. Since Ben 10 has the elephant in the room that is Alien X (and probably some other stuff I'm not aware of) and I remember hearing some universal shit with Elden Ring's endgame. (Gonna ping @OtherGalaxy and @Atem for more info on this one)
Elminster might win in a speed-unequal scenario with his hax, due to being superior to adventurers who can tag and react to Kezef the Chaos Hound, who can travel 2.935 quintillion c. Its CR is 21.