I main both the ICs and Olimar, so this discussion is heavenly to me ^_^
IC 45 - 55 Olimar
IF they manage to grab Olimar, he's done for. However, actually grabbing him will prove to be difficult, since Olimar can just spam f-smash, d-smash and u-smash with a yellow Pikmin. He outranges them severely, and beats their air game.
The Ice Climbers, however, have a lot of use for Blizzard in this match-up (beats out all smashes), and u-smash will chop up the light Olimar. There's also the strategy of d-tilt to edgehog, which always works quite well for me... In other words, it's mostly about who gets the hits in first.