All bonuses:
Enter ZENBU as a profile name.

Unlock Professor Gutenburg
Go into adventure mode and go to the torpedo run. Three subs will display on your 
radar. One of them is a yellow sub with the professor on it. Unlock the code by 
shooting two torpedoes at the yellow sub.

Unlock Sammy Wasabe
Go to monster isle. Shoot a ninja by the shrine in the middle of the jungle. If you 
did it right it the guy will say "you unlocked sammy wasabe.

Unlock Island Jack
In adventure mode go to danger island. when you get to the jungle go below the 
trees. when you see a giant snake wrapped around a tree branch near the end on 
the left side of the jungle shoot it and you will get island jack

Andre LaToilette
In Bigfoot Mt., when you start in the beginning of the level you will see a house on 
a hill. In front of that house is a snowman, shoot the the snowman and if you shoot 
enough it will say you have unlocked Andre LaToilette.

Get Sheik Abdoul (the Arabian man with the rocket powered flying carpet)
In the Cave of Blunders, you start above a Arabian city; in the center of town 
there is a small area (with pillars) where Sheik is being bullied by a palace guard. 
Kill the guard to get Sheik Abdoul.

Cactus Rose
In the beginning of Coyote Canyon on your right will be a town.In that town there 
will be a girl being hanged. Free her by shooting her and it will say you've 
unlocked Cactus Rose. 

Unlock Everything:
Start a new game with ZENBU for the name.

Sven With Monkey:
In Torpedo Run, achieve a perfect score.

Zenbu:
Unlock everything in the game to get this character.

Stewardess Traci:
In Bandito attack, achieve a perfect score.

Sanitation Paulie:
In Thugsville, achieve a perfect score.

Sambot 5000:
In Monster isle, achieve a perfect score.

Monkey Pie:
In Intestinal Track, achieve a perfect score.

Margaret Basher:
In Thugsville, head to the harbor and shoot the union Jack flag on the ship under 
the bridge.

Marcel Clowns:
In Bombsburg, achieve a perfect score.

La Chiquita Diabla:
In Coyote Canyon, achieve a perfect score.

Human Baron.
In grave danger, achieve a perfect score.

Chicken Hut Sheik:
In cave of boulders, achieve a perfect score.

Bigfoot:
In X, achieve a perfect score.

Baron Von Slaughter:
In grave danger, fly into the graveyard and destory the baron's tombstone.

Automatic Aundre:
In bigfoot mountain, achieve a perfect score.

Pilot X:
On the last level in Adventure mode, X, beat Pilot X by destroying his robot. Pilot X 
will become a playable character in all modes except Adventure Mode.