Thanks to those that replied. Insightful stuff. From what was said, I get the impression that the "dealing with Pikmin" game is something that could really swing in either player's advantage depending on how it's played. Having Pikmin latched onto you can leave your approaches more vulnerable due to extra hit-lag, never mind the free damage Olimar gets with it, but Olimar players need to be careful not to leave themselves with too few Pikmin in the process. Sound about right?
And yeah, the ideal would be to avoid having them latch onto you at all, though in practice that is of course easier said than done, especially for big targets/characters with low mobility. Getting a bit character-specific for a moment, I think I have a good idea of which attacks Ness has that are good for killing Pikmin stuck on him, though some depend on where the Pikmin are on him as well (head vs. midsection, for instance). Other characters undoubtedly have their own moves for the job, and if I'm not mistaken, most Pikmin have less health in this game, which should make it easier to kill them if you choose to. On that note, has there been any research regarding exactly how much health each kind has? I've been looking around but haven't found anything yet, so I tested it out in Training (in case staled moves would deal less damage to Pikmin as well, though I haven't examined that yet). From what I found, it was something like Red/Yellow=8 HP, Blue=11 HP, White=7 HP, and Purple=13 HP, though additional accounts would certainly be helpful in that regard.