This is mine short guide to beat mercenaries mini-game and unlock handcanon.
For walktrough you can visit this user. Great guy, great walktroughs, he also jokes about enemies and other stuff while playing. Best choice!
http://uk.youtube.com/user/NintendoCentral
And now help with mercenaries game...
FIRSTLY COLLECT ALL EXTRA TIME CLOCKS! AIM FOR ENEMY HEADS!
Leon
Village - Be fast, and raise your kill combo. After you kill first 2 Bella sisters, collect extra points clock (30 second extension that gives 1000 points per kill). And thats all what you need to do basically...
Castle - Same as above, its easy to score lots of kills. Avoid Garrador if you want, but i suggest you to kill him to dispose of him, so you wont have big problems later... Use Shotgun.
World 3 - Same as above, but be careful, there are 2 Machine gun maniacs. Use shotgun to dispose of them.
Water World - Be extremely careful, and do not get close to the double chainsaw maniac if you are not professional player. Its quite easy to kill them. Run somewhere near explosive barrels and wait till he gets close to it and than shoot the barrel. He will be injured. Use granades to finish him of, or if you dont have any blow his head off with shotgun. Other enemies will be piece of cake.
Ada
Village - To kill Bella sisters use sniper rifle and shoot their head.
Castle - Same as Leon, use sniper rifle when you are in serious problems.
World 3 - Same as above, but be careful, there are 2 Machine gun maniacs. Use sniper rifle to dispose of them.
Water World - Same as Leon, use barrels to damage chainsaw maniacs, and finish them with granades or sniper rifle.
Krauser
Krauser is my favorite mercenary. You can own every creature.
Village - Raise your kills on poor villagers Razz. Save special move until you fence Bella sisters. Try to kill them both with one row. Also this move can score good. Collect bonus time clock and use it when there are more than 5 enemies, each close to another.
Castle - Special move FTW.
World 3 - Special move FTW. Dispose of machine gun junkies.
Water World - Easiest way to kill maniacs is to use special powers. 1 kick kills them.
Hunk
Hunk is another good mercenary.
Village - You have grenades, use them for multiple combos with bonus time. When Bella sisters come, shoot one in head and if she gets shocked (if she starts tumbling) go near her and preform neck breaking move, and you will kill her with 1 move. Its good way to raise kills too.
Castle - It will be harder to kill Garrador. If you know what you are doing you can use grenades on him and shoot his back. If not collect bonuses near start and go trough door to upper floor. Collect all bonuses and use them while you can and move to upper floor, until you reach final destination, the place where will short cut-scene appear. Stay there and raise your combo, its best place. You wont face that boring Garrador if you stay there.
World 3 - Use grenades for machine gun junkies.
Water World - Barrels and grenades.
Wesker
Wesker is strong merc too. USE HIS SPECIAL MOVE WHENEVER YOU CAN.
Village - Dispose of Bella sisters, and villagers wont be problem.
Castle - Let the Garrador hit wall and when he is stuck use magnum to kill him.
World 3 - Magnum and grenades are good to kill machine gunners.
Water World - Use special move when you can, and if you can on maniacs to kick them far away from you. Use barrels and grenades. Use your magnum too its powerful enough to kill them.