Hi!! This is all password description that i know to start episode 2 to 6. I list the best to the worst one. Feel free to fill up the list. Sorry for my bad English.

LEVEL 2

• VTTJHD (96 minigun, 5 Life)
• VVKJJF (96 minigun, 4 Life)

LEVEL 3

• SNKLFN (96 minigun, 10 Rocket, 8Life)
• SNTLFN (96 minigun, 10 Rocket, 7Life)
• STTLHT (96 minigun, 10 Rocket, 5Life)
• STMLDM (10 Rocket, 5Life)

LEVEL 4

• MCKLTP (96 minigun, 30 FlameThrower, 10 Rocket, 8Life) Best
• MCSFCV (84 minigun, 10 Rocket, 7Life)
• MCJLJQ (80minigun 10 Rocket, 8Life)

LEVEL 5

• KNKLMR (96 minigun, 30 FlameThrower, 10 Rocket, 8Life) Best
• KNJQVN (92minigun, 30 Flamethrower, 10 Rocket, 8 Life)
• KNDQMR (44minigun, 30 FlameThrower, 10 Rocket, 8Life)
• KNDVRM (40 minigun, 30 Flamethrower, 10 Rocket, 8Life)
• KNCVVN (24 minigun, 30 Flamethrower, 10 Rocket, 8Life)

LEVEL 6

• JNKLQN (96minigun, 30 Flamethrower, 10 Rocket, 8Life) ** Only one i know for Ep 6**

It surely exist more and maybe better. Like i said feel free to fill it up.