It depends on the player and the mu.
ICs don't really have a bad stage, just little problems on different stages.
I'm definitely a small stages IC. My go to stage is Yoshi's, then FoD, then BF.
But a lot of ICs are the opposite and like having space on FD, Dreamland, and stadium.
Most people auto-ban FD against ICs, which is fair in a few matchups, but it depends. Generally, most IC players when they are new are told "ICs are broken on FD because it was chu's best stage back in 2003" so most ICs are super comfortable there, even if its not their best stage in a particular mu.
That said, a lot of ICs (and smashers in general) are super lazy about their CPs and just auto CP fd if its not banned.