Glitches (or bugs) are oversights in the making of a game that lead to unexpected results, and are exclusively a flaw of the game's software. These can be triggered by the player accidentally or on purpose, and can be beneficial, harmful or harmless. Some glitches are abused in order to successfully complete otherwise impossible challenge runs.
There are four articles on this wiki that list glitches in Pikmin games, organized by game:
In addition, there are other pages that go into more detail on certain kinds of glitches:
It is recommended that you read the glitch notes before attempting any of these glitches, or before adding your own.