Wat? ICs have like 2 or 3 bad MUs lol. They have a few 45/55s, but they only truley lose to Snake and Rob.
Most chars air games are totally shut down by blizzard, and if you approach from above, you eat the infinite priority Uair, like 3 times.
Characters who beat ICs are ones who make them approach very well (rob lazer,, snake nade, (falco is a good MU, I'm just giving the lazer as an example of what makes a good approach forcer) falco lazer) and shut down their approaches (which is only snake, and kinda rob. Desynched blizzard outranges pretty much everyone elses moveset.)
Marth and Gaw and MK are 50/50 to 45/55, but if you are calling those bad MUs, then lol.
The biggest flaw in ICs is that they do badly on lots of stages, but most are actually managable if you practice on them and ban brinstar.