Activate the following cheats by pausing the game, holding BLOCK, and entering the corresponding sequence of buttons:

CHEAT FUNCTION - CHEAT CODE
Shadow Crash - KICK, PUNCH, KICK, JUMP
Big Head Crash - PUNCH, PUNCH, KICK, JUMP

Complete the game to unlock the "Ye' Old Skool" Move with infinite spin time.

Complete the game under the Hard difficulty setting to unlock the Free Kick move.

Unlock the following skins by performing the corresponding tasks:

SKIN - HOW TO UNLOCK
Battler - Jack 35 Battlers.
Bratgirl - Beat 130 Brat Girls.
Doom Monkey - Beat 500 Doom Monkeys.
EE-Lectric - Jack 50 EE-Lectrics.
Goar - Jack 30 Goars.
Halloween - Complete 50% of the game.
Koo-ala - Beat 150 Koo-Alas.
Magmadon - Jack 50 Magmadons.
Ratnician - Beat 200 Ratnicians.
Rhinoroller - Jack 30 Rhinorollers.
Scorporilla - Jack 15 Scorporillas.
Shellephant - Jack 15 Shellephants.
Sludge - Jack 50 Sludges.
Snipe - Jack 50 Snipes.
Spike - Jack 50 Spikes.
Stench - Jack 50 Stenches.
Valentine - Collect all Gold Idols.
Voodoo Bunnie - Beat 200 Voodoo Bunnies.

To easily jack a creature, wear a skin that matches it. You will then be able to knock out the creature with one hit.