Honestly, Ironically considering first Olimar impressions, I've found Olimar does not do great with projectile spam. He can overpower some characters doing this, however it costs pikmin and over time requires more pikmin, which is down time, and thats where the idea of constant pressure comes in, make it had to get more and olimar's options become limited, not to mention the player is now focused on looking for an opening simply to draw more pikmin, taking his priority off of doing maximum damage to you.
Another short coming of Olimar's I've experienced so far is the very close range, if a player is able to move in effectively on olimer, to within that FSmash/grab distance, things start getting really squirrelly and often results in a mess, as olimars only real option here is the DSmash which can be beat both in speed and priority by a large number of moves. Obviously getting safely into this range is a challenge, but as much as Olimar mains work on strategies to prevent just that, I'm sure others are finding ways to adjust and accomplish just that, and I expect it'll become a breaking point for the outcome of any match.
These and some of the things listed above certainly "limit" olimar, but he has been given a strong move set no doubt. Fortunately I still see this as in balance and not over powered nor under powered, though time is still the only one who can tell. For what its worth however, I also think most people are over reacting about marth's supposed broken unfair strengths, so perhaps i'm not seeing things clearly yet. Thats my two cents either way though, we shall see.
-True