Uhhh...
Having mediocre IC players not being able to cg you doesnt effect the matchup.
Grab dthrow walk in front, fthrow regab is one way which doesnt really change per character, although its one of the trickier ones..
ICs win imo not because of CG but because of what they do while you take precautions not to get CGed.
Desynched blizzards **** yoshi so bad, yoshi cant shield it or he gets grabbed so he has to jump or run away if he jumps the desynched nana can just uair you, then you are above ICs which is a terrible spot to be.
Its a momentum based matchup, and yoshi has good tools to eff up their momentum, with his grab on landing and such, but ICs are simply a much better character with a much better pressure game and the best punishment in any smash game.
Also desynched iceblocks can be a pain XD