Pikmin 2 Glitch List
Below lists some of the found glitches in Pikmin 2.
 Out of Bounds
In the Wistful Wild region, it is possible to get "out of bounds" with you, the president and your Pikmin. To do this glitch takes a long time, as it requires using the Armored Cannon Beetle Larva near the Electric Gate. If you let this creature go up to one of the walls, then go in and attack it (using your fist obviously) it will eventually Buck, after spitting a boulder. If you stand in front in the right position you can be sent up the wall by the power of the buck. Sometimes (on the right side is more common) the rocks go up as well or glitch and keep rolling and rolling next to a wall, and then they eventually break (sometimes hitting the cannon beetle to, lowering its health).
When out of Bounds you can get the President (Or Olimar if the president is up there) to throw up some Pikmin and then repeat the glitch for himself. Once up there you can't keep going out and out and into the black void as there is an invisible (and invincible) barrier blocking your way. You can't cross over the gate to dream den as there is another barrier blocking that.
Once finished just walk off of the wall.
 Absorb a Spray Twice
Sometimes in Pikmin 2 it is possible to absorb a drop of spray twice, making two sprays out of one drop. To do this, you must take one captain, put him in front of the spray, dismiss, swap captains and then take the other captain and run up to the spray. Right before you hit the spray, quickly switch captains. Then run up to the spray yourself with that captain, and both captains should be absorbing it.
You will then get two out of one spray.