To get the secret Rocket Pack for any character, find the rotating platform with the jump on it (which occasionally raises into the air) and go off the jump. You will obtain a Rocket Pack for a short time, but will still be able to use your other weapons (except Gunship, which is also a flying weapon). Use this with the Cluster Bombs weapon to rain bombs on your opponents, or with the Machine/Tommy guns to become a turbo-charged Gunship.
Count Earl: Easy kills
When playing on Smack Attack with Count Earl on Wild Wooly West, get his personal weapon. On the railroad bridge go straight. When you see someone coming on either side close to you fire. Count Earl's seeker missiles should kill your opponent easily.
Flemming: Easy kills
As Flemming, get his personal weapon on the first desert world level. Go to the end of the train tracks, then turn around. When someone approaches, shoot nonstop.
Gate Rally Mode
To unlock Gate Rally Mode, you need to accumulate one win in Smack Attack Mode. If you've played, then you know this is not easy. An easier way to accumulate the one win you need is to plug in three additional controllers and play on the space level. The three uncontrolled opponents will always spawn on the upper ring around the level. This leaves them wide open for you to kill, but they're ignored by the CPU controlled players. You should be able to rack up enough points to win by killing these sitting ducks.
Get All FMV's
Put in MULTIPLEX! as your name
Get Count Earl
Put in COUNTDEAD as your name
Get Hazardous Weapons
Put in HAZARDOUS as your name
Get Jungle World
Put in TWRECKSPAD as your name
Get Movement Power Ups
Put in MOVEITNOW as your name
Get Pen & Ink Mode
Put in PENCILS as your name
Get Personal Weapons
Put in UNIQUEWPNS as your name
Get Ranged Weapons
Put in GUNSMOKE! as your name
Get Space World
Put in BRAINSALAD as your name
Get Whack Angus
Put in WHACKFAD as your name
Invincibility
Enter CODY as a name.
Spin on the ground
Go top speed then hold L + R. Press Left or Right on the Analog-stick. If done correctly, you will start spinning.
Unlock All Desert Stages
To unlock all desert stages, enter the name WHACKLAND as your character name to begin a game.
Unlock Everything
Enter your name as ENCHILADA!
Whack Angus: Easy kills
On the first desert world level, get his personal weapon. Go near the end of the train tracks, then turn around. When someone approaches, press A.
