Fire - Good for setting enemies on fire, but not that useful. In one boss battle, you will need it.

Electric - Needed for charging up the blue orbs that aren't lit up. Shocks some enemies into submission.

Helium - Blows up the bunny (no, not really, but you wish) with helium so that you can float. Use the right
trigger to slow your descent, or use your tail as a rudder with X.

Ice - Freeze enemies. If you keep hitting them while frozen, they will break and disappear (see Glitch section, though).

Toxic - This is is how you're SUPPOSED to get into decontamination, but..