Onions
Red Onion
Houses red pikmin.
Yellow Onion
Houses yellow pikmin.
Blue Onion
Houses blue pikmin.
Other Ships
S.S.Dolphin
Olimers ship from pikmin 1 (complete version).
Research Ship
Olimer and Louie's research ship from pikmin 2, houses purple and white pikmin.
President Choochoo's Ship
It is solid gold. It houses purple and white pikmin. (No wonder they went in debt)