@ whoever mentioned Kirby stealing Samus' power...I find that homing missile seems to knock that power right out of him a majority of the time. No data or other reason why.
General...agree with Utilting Kirby out of his upB.
Learn the Kirby player's shielding/rolling and exploit with grab. I usually do Uthrow because that's where I like Kirby to be.
Also, I feel like writing up something longer on Olimar (even though we're more or less done discussing the character).
Always try to keep a projectile between you and him. Yes, I know that pikmin toss beats out missiles and charge shot. That only works if Olimar throws pikmin. If he tries to grab you then that projectile he did not destroy will break the grab because Oli has no grab armor.
If Olimar is getting too close to you (approaching max grab range) then you're usually safe to lay a bomb (watch him to make sure he has at least a tiny bit of lag). Bombs let you use missiles/Zair to create more pressure and space which is good for your defensive game.
Zair (obviously) stops pikmin in flight. If there is a missile in flight then feel free to SHNair any latched pikmin as it will be very hard for Olimar to punish you for it. The Zair/missile combination will stop a majority of pikmin spam. I like Dtilt/Ftilt at max spacing in this matchup because they are difficult to punish OoS when used intelligently.
Don't forget to grab, especially at lower percents. Olimars start to think that their shield shuts Samus down in this matchup, so you need to remind them on occasion that it doesn't.
In this matchup, I will normally get so close to shield-break that the Olimar's shield stops working for almost all attacks (Fsmash and tapA will usually always be useless to me). This matchup will require a LOT of patience.
An important part of this match is to realize when Olimar is defending and when he is retreating. You can usually tell the difference because there will be a hole in his flow. Use projectiles/Zair to pressure him as he reaches his 're-established spacing point' to keep him off balance. If you're successful here then this is where you'll land a big part of your damage. My usual combo starters here would be Dsmash and Uair, but it is different for everybody.
There is almost always a safe way up from the ledge. Just look at where Olimar is standing to figure out what your best option is. When he's close to the edge, I like both Uair through the stage and edge hop retreating Fair. Uair can poke through a surprising number of stages (Lylat and Rainbow included). With Fair, you're aiming for three hits on his shield before DIing away and back to the ledge. It'll eventually weaken his shield and has no OoS option when spaced correctly. Edge hop missile works when Olimar is shielding grab range from the edge as it prevents him from grabbing (you must land on stage with a missile cancel or this won't work very well).
Off-stage game is pretty straight-forward. Edge canceling Zair or homing missile forces Oli to either air-dodge or armor cancel. If he doesn't then just follow-up attack with rising Zair or missile/Nair respectively. If he armor cancels or airdodges then weak Nair all dai. It gently nudges him away from the stage. Also, if you're feeling adventureous, run off the edge, then downB and DI back on stage. If you time it correctly then Oli gets hit out of the 'recoiling to the edge' animation and it's an easy edge hog. If he waits out the bomb, either a weak Nair below the edge or the auto-sweetspotted upB back to the edge will hit him and you'll usually get the edge hog.
For stages, I go anything with platforms. Lylat, Battlefield, etc. It's relatively easier to get Oli stuck on a platform, and Samus can capitalize with her air game here. Stages to avoid would be anything uneaven. Samus only has horizontal pressure in this matchup. Eventually she will need to control the middle of the stage, but this is impossible when uneven terrain prevents her projectiles from working properly.
Final thoughts: projectiles lessen the effectiveness of Oli's camping and eventually weaken his shield. Samus does not fight this matchup. Rather, she gradually convinces Olimar into a location on the stage where he is far less effective, then deals damage as he tries to escape. A smart Oli will not go airborn because Samus has easy damage-dealing there.
I would put this matchup at Sam 40:60 Oli. Olimar has the advantage, but this is not one of Samus' worst matchups. If you play smart and patient then you will find exploitable openings.