The Puffstalk is an enemy encountered in Hey! Pikmin in Sector 1-C; Mushroom Valley, and in Sector 8-X; Burning Bog. It hides within holes in a cave wall, popping out of one and occasionally switching holes. It has no means of attack, and therefore cannot harm Pikmin. In Brilliant Garden, it drops the Constitution Gate when defeated. In Lushlife Murk, it drops the Tangerine Paste.
Hey! Pikmin Creature Log
"A mysterious creature that likes to pop out of its nest and then go right back in. It's bent on collecting energy-rich objects. But then, so am I, hmm?"
The Puffstalk can't harm Pikmin, so all you have to do is pay attention to the hole it comes out of and keep throwing Pikmin at it until it dies.