i have lot of experience in the matchup, i have fought Dabuz a great olimar main and i dont suggest many random SHUair when hes distanced and youre in high%(70+) cause the Usmash by red and purple can be deadly. you can space in this matchup, which is unique cause oli ***** most chars camping. i dont suggest using your neutral B, because his pikmin would be in the way and mess you up. watchout for his pivot grab, its the best in the game so he'll be using that alot.
now w/ the Q: Campy olimars tend to throw pikmins (side b) and when you approach, they will Fsmash, if they miss then they might Usmash(if youre on top of them) or/and pivot grab.
after a sidestep ALWAYS esxpect a Smash, probably a down smash.