By "they" I'm assuming there's no arguments against Diavolo's team.
Squalo - Minor damage to Chisake if wet, or distraction.
Tiziano - Could support one team mate by placing Talking Head inside them without activating its ability.
Like in this video (0:40, 1:40).
Carne - I can see B. I. G. dealing most of the external damage to Chisake AND as a major distraction.
Chioccolata - Can disintegrate Chisake if given the right circumstance (Chisake doing a mega-jump).
Secco - Can swim inside Chisake and deal internal damage by melting his body, and given the opportunity, deal with Chisake himself.
Diavolo - Can climb up to where Chisake's body is and blow his head off.
Working in tandem, we get:
Chisake's main focus being on B. I. G. kaiju style.
Secco weakening Chisake's muscle joints so he collapses to the ground, allowing Chioccolata to damage him further. Also causing Chisake to bleed in areas around his body, allowing Squalo to distract him.
Tiziano planting Talking Head on Crush, allowing it to distract Chisake while staying inside his blood, teleporting if needed.
Diavolo potentially striking a killing blow if everything lines up for him to sever his arms or blow his head off with a sneak attack.
Thoughts?