1) The pikmins are invincible while they are with you. Also:
2) He plucks pikmins very fast.
anothers
3) Best range of fsmash, dsmash, and grab.
4) Speed
5) Size of the character (like pichu)
6) Great knockback
7) Good aerial game, and a sheik-like fair
8) Is Olimar ****.
9) Pikmin owns: throw them and see how your opponent cant throw missiles to you (pikmins stop them) and also how his damage counter grows faster and FASTER: ops, he's death xD
Only reason why it's bad:
Tether recovery=owned by ledgethievering. A competitive tech (casuals don't use it much). So anyway, it will be near god in casual way, and very good in competitive way.
Resume:
1) Best range in smash
2) Best range in grab
3) Best and quickest projectiles
4) Quick, good aerial game, and small