Other characters that use moves with disjointed hitboxes will be a challenge. As far as I can tell pikmin themselves have very little priority, and when met with other disjointed hitboxes (eg swords hammers etc) the pikmin don't stand a chance. Notice in the marth games how a typical Fair approach is immune to latch, every thrown pikmin is simply batted away usually without even altering their timing.
Latch probably is a little overrated at the moment superryan, if your only looking at it for its damage done in a match. Throwing however is much more important than the damage it directly causes, think of the way peach uses her turnips competatively. If you need more explanation see post 23 of "Is Olimer too powerful?"
Both for damage and anticipation however, a disjointed hitbox that easily dispatches pikmin removes both advantages, and will likely cause Olimer the most trouble. So Marth, MetaKnight, Toon Link, Link, Pit if those short swords are disjointed, Ike if he can swing his sword quickly, DeDeDe if hammer attacks become staple, Ice climbers same deal as DeDeDe.
-True