Charge Man's stage is a departure for your normal Mega Man stage in that the level is actually set on a moving train.
The level is as straightforward as they come, serving as more of an all-out challenger than one that will leave you scratching your head. The enemies are pretty easy to kill, and the Beat Letter is in plain sight, easily snatched up with the Rush Coil.
Charge Man himself is a frustrating boss to deal with. Not hard, just frustrating. He has two main attacks - firing red coals into the air, which rain down on you, and charging at you (does the latter one really surprise you?) He's only vulnerable while moving around the battlefield at normal speedm, and is NOT vulnerable while doing either of his attacks. Technically, his weakness is the Power Stone, but it's so hard to aim and hit with, that I just recommend using the Mega Buster. Just don't shoot until you know he's vulnerable.