Woot!
Loved this man. Great amount of fun. Each unlockable had his own strenghts.
Santa: Neutral (to be used as comparison for other characters)
Alien Hominid: Jumps high. Goes higher when shooting the ground than Santa does. Gun does more damage. Less life (40HP)
Pbot: walks a bit slower. Jumps real, but has little control over direction of movement. 100HP. Attacks does more damage.
Pico: Fires fast. Real fast. Less life (60HP i think). Does 5 damage. Jumps are decent.
Shark guy thing (don't know name): Jumps low. 7 Damage. Can't remember life, but i think it's 30. Rockets make big explosions. Best part? Water doesn't kill him. If he touches water, he jumps real high. Extremely useful for those levels where water keeps killing you. REALLY useful when fighting final boss. Stand in the water and wait for him to come to you.
Tips for boss: The giant boss is actually a real easy 2 second boss. When you see him, shoot him once, he'll follow you now. Run to the left, all the way to the wall. Then just up the wall. You'll be out of his reach, and can easily shoot the guy off his back. Then just shoot the icicles. This is a fast match for Pico and Pbot. But it's just as easy for everyone, and so therefore, use the shark, cause it makes the second half easy.
Second half: Find lowest land, and stand there until he fires at you. Jump up at the last second and a piece of land will be destroyed. Jump into the crator and wait for another attack, jumping again at last second. Water should appear by now. This is why you should be the shark. Stand in the water (you'll be jumping). Just stand there and wait for the guy to come to you. He'll drown. You'll win.