MEGA MAN 10
12 Achievements
200
12-15h
TRUSTY SIDEARM
Defeat the 8 bosses with just your default weapon.
20
How to unlock the TRUSTY SIDEARM achievement in MEGA MAN 10 - Definitive Guide
Just as it says: use the Buster exclusively on the 8 Robot Masters. You can accomplish this on each of their independent levels OR in Area 4 of the castle. If you are trying for this trophy early on, just be sure to bring at least an extra E-tank with you into the fight ... just in case. You can earn this trophy by playing as either Mega Man, Protoman or Bass.
Attempt this on easy, the bosses move much slower and deal far less damage than other difficulties. Try to dodge as much as possible and shoot as fast as possible. You can buy energy tanks if you need an extra life refill.
This may be a little tedious to remember while playing through the game. When you get to Wily 4 you will have to fight all the bosses, one after another. If you don't want to remember to change your weapons this will be the perfect place to do this achievement.