@Supreme Marvel: She is still suceptible to mindbone and possibly electricution. and no they can't. Wouldn't be fair. Thats why I cut out legendaries.
If we're gonna go purely by feats: ash stomps
no pokemon has ever been shown to die due to an attack. even the most ridiculous mismatches do not cause pokemon to die, they just faint. pokemon only ever dies in extraordinary situations. it doesn't matter what feats starfire can pull off. pokemon, after tanking absurd damage, will just faint. also jesse and james have been shown to tank all sorts of attacks e.g. numerous pikachu thunderbolts, explosions and burns and survive. since they dont have superpowers, it is clear that ash will survive disproportionate damage as well. since the fight is to the death, ash wins because he and his pokemon can't be killed and ash never ages. all ash has to do is wait for the teen titans to die of old age.
if going by reason: raven telekinetically steals ash's pokeballs robin chokes him gg.