I dislike YIB in the MU because the stage makes Olimar's grab range slightly longer in some areas as well as the curvatures makes the difference in some of his cooldown animations having grab whiff on approach. Dash grabbing a whiffed Olimar Dair only to have it go over him is the worst feeling. I like smashville the most, but I'm not too concerned about juggling Olimar for damage because of whistle. I'm more focused on getting him off stage.
The only thing I'd differ with V115 on the MU is that I think Bair is probably the most important tool we have in the MU. If you space with the move with some precision, you cover yourself from a lot of option Olimar can use to punish, even if you hit on shield. If done right, jab/spot dodge after Bair forces the Olimar to guess in a 50/50 just to punish you. Especially if you use your jumps and platforms (especially platform cancellable ones) intelligently to bait options, you'll more likely than not be able to get in.
Nairing when you have pikmin latched on you as a landing option is actually a pretty gimmicky mixup. The extra hitlag from Pikmin makes instant lingering hitboxes. Plasma Whip on pikmin returning to Olimar also creates a small hitlag trap that can be hard to track (since Olimar's will try to dash to shield grab that move)
Don't airdodge into the ground when landing against Olimar unless you have some sort of hard cross over read or have conditioned them to hell and back to expect an aerial, and even then it's really risky. Try to zone so that your landing option is Bair, but if you can't, mixing up between Nair (primary) and Fair (on read) is almost always better than air dodging. If you feel threatened, throw out that jab after landing because even on shield you can sometimes bail yourself out and catch a shield drop option.
If you grab Olimar at around 100-110, don't bother throwing in my opinion. Go straight for the pummel > forced ground break > guaranteed jab string to refresh moves. If you get another grab at 130+, GR Uair will kill most of the time. But this is important because by this percent you've generally been using Bair to zone the whole stock, so you now have two reliable kill options from the air (Bair/Uair), one gimmicky one on the ground (plasma whip), and one out of grab (GR > Uair).
When Olimar is in the air, if there are platforms spaced uair pressure is pretty solid per every matchup because they can't go through platforms while whistling. However, if there are no platorms, don't bother chasing Olimar in the air since the cost of them whistling through isn't worth it. Just cover all of his options by waiting in shield and punishing with dash attack to get them off stage. Once they are off stage from the ledge, you can start mixing in other landing punish options like pivot grabbing them or dsmashing them. If you can get them off stage and too the ledge, that's where a majority of the winning trades are. Everything else is kind of a push unless they get under us.
Trapping Olimar is shield with Jab is pretty broken, and you should do your best to try to jab them out of their fairly slow moves oos by timing their reaction time.
