Pellets are items in the Pikmin universe used to generate Pikmin when transported to the Onion. They are created by hardened nectar from Pellet Posies, which, when attacked, will drop the pellets. In Pikmin, the number on the pellet signifies how many Pikmin are required to carry it. In Super Smash Bros. Brawl and Super Smash Bros. for Nintendo 3DS, they appear only in the Distant Planet stage, where they grow inside flowers called Pellet Posies. Pellets come in three colors: red, yellow, and blue (each corresponding to an onion of the same color); and in three sizes: 1, 5, and 10. Pellets gradually increase in size if left to grow on their posies. Higher numbered pellets also deal more damage and knockback when thrown.
Pellets can be used either as projectile weapons (causing damage proportional to their size), or they can be thrown into an Onion to produce various items.
Any kind of pellet can be thrown into any Onion, but if the color of the pellet matches the color of the Onion, then extra items will be produced. It is a common misconception that better items are received for matching colors or larger pellets, but in fact, only the number of items spawned changes.