The elbow smash (+) is one of the most powerful moves in the game and can also be used to attack enemies behind you.
If an ememy is carrying a stick of dynamite, let them throw it at you. Then walk backwards away from the enemy and dynamite. The enemy should follow you and walk right into the explosion.
Use you grapple to grab an ememy and then throw them into the traps and pits that are scattered throughout the game. If you time this correctly, you can even coax the enemies to walk into traps without you touching them.
Some enemies carry knives that they will drop when attacked by Billy or Jimmy. Use these enemies to supply you with knives to help defeat the other enemies on the screen. Pressing kick when standing next to the barrels and cartons will sned them flying across the screen.
The weapon you are carrying can sometimes be taken into the next level if you are standing in the correct position when your character discards it.
In a 2 player game you can hurt the other player, so be careful.