I think the basic thing with this match up is knowing HOW to approach.
Falco obviously has the upper hand up close, which is undoubtedly Olimar's weak spot. However blindly rushing in will get you grabbed, as will likely approaching through the air.
Most Olimars will try to pivot grab your landings, since it's probably the safest way they can grab. I think air dodging in is a viable option, as long as you jab or f-tilt quickly enough so they can't throw out a second grab in order to kill you.
I think it's been pointed out that you can jab most pikmin he throws at you and shield purples, so that solves his camping, which obviously isn't that much of a problem since we can out camp him with lasers.
Watch out for OoS upsmash, grabs and also, pay attention to his line, it'll help you figure out his next move.
Pikmin work in the following manner:
White - highest damage when latched, farthest throw range and farthest grab range. Their killing potential is zero to none and they will more likely just be thrown most of the time, especially in high percentages.
Red - Best aerial knock back, mid throw range. Will most likely be used for f-airs and b-airs.
Yellow - Disjointed hitbox, small throw distance. Will probably be used for spacing with F-air, F-smash, and U-smash in high percents, though it can kill very well.
Blue - Second best grab range, good for f-smashing and at mid-to high percents can start killing with b-throw.
Purple - shortest ranged throw pikmin but don't latch, will hit you and stop your movement. Can u-smash kill you as early as 82% and also can kill with up throw.
One last thing, remember that he can grab out of the ledge and smash just as well. Also, no grab armor, so use that to your advantage.
Edit: forgot to mention that putting Olimar in the air is extremely useful, although I don't know how to juggle very well so I can't add details pertaining to that, but putting Olimar in the air will always give him a tough time, since he has a very hard time landing. Predict them whistles.