Daffy Duck: The Marvin ... Cheat Codes for Gameboy

Weapon Select
Earn ten points after defeating ten enemies, then pause gameplay. Enter any of the following controller actions for the corresponding weapon or bonus.

Item Code
Laser Up(2)
Big Bullet Down(2)
Bouncing Left(2)
Rapid Fire Right(2)
Health Refill B(2)
No change Select

Level Passwords
2 72308
3 04070
4 82048