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
Unlock prof. gutenburg:
Go to adventure mode and go to torpedo run there will be three subs on yor radar one of them is a yellow sub with prof. gutenburg on the front shoot two torpedoes at it and you will unlock prof. gutenburg
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.