Arzaki

It's a penguin in a penguin mech with missiles, a big fist thing, a flamethrower, and the ability to dash across THE ENTIRE ARENA AND KILL YOU IN ONE HIT. It also has this thing where it shoots a spray of pretty big bullets throughout the room and deal take out like a quarter of your health. Even with THREE regeneration buffs, I can't beat this guy. The problem is that since I mostly use guns, I need the high energy armor which doesn't have much defense, while the defensive armor...

Dangit BZP, stop cutting off my posts.

...while the defensive armor gives almost no energy. This guy can kill me in like 4 hits.

It doesn't help that the arena is about a screen wide and IS COMPLETELY FLAT. It's almost impossible to dodge his flamethrower if you don't have the entire room to run across.