>>24950466Chesnaught was difficult because of the blocks but I managed to pass it itemless because its only 3 mons and M Charizard brought a bunch of combos.
Delphox was slightly easier but you have to break the ice blocks real fast in the beginning. Passed it itemless.
Greninja is the hardest of the 3 because it uses it pre evos. It's possible itemless if you have a strong enough team, otherwise use +10 seconds if you have trouble.
That's as far as I got.