He only hardcounters DK and DDD, who are huge targets.
G&W outcamps Olimar, and has very good edgeguarding on him and can juggle him, so he has the advantage in the matchup. If Olimar whiffs a grab, he does get punished anyhow with a B-air, and it's not hard for G&W to limit Olimar to ONLY grabbing by simply D-tilting, which can't be punished at all by Olimar unless G&W does it wrong.
MK I dunno honestly, I hear that his priority is funky vs Pikmin, but otherwise the matchup can't be that bad for him since he has gimps.