I checked the characters who can be chaingrabbed up the slope on Distant Planet on Yoshi's Island (Melee) by King Dedede. Here are the results.
Grabbed:
Donkey Kong, Wario, Link, Ganondorf, Wolf, Lucario
Not Grabbed:
Mario, Peach, Bowser, Toon Link, Samus, R.O.B., King Dedede, Ivysaur, Charizard, Snake, Sonic
Also, Yoshi can't chaingrab Donkey Kong up that slope which means the only character Yoshi gets a regrab on is straight up Wario (who is caught in an infinite at that point on every stage).
Falco can chaingrab Snake up that slope I'm pretty sure and probably some others, but I don't know how big of a deal Falco's chaingrab is since it's percentage dependent and whatnot. The timing on it also probably varies with the damage the opponent has which makes it a real pain to test. Either way, I doubt it's particularly broken given how it's damage dependent.
If this stage is broken in general, I don't think chaingrabs are the reason.