Another outstanding title that gave me the magic of multiple worlds idea when I was younger.
Back in Highschool I used to multiplayer emulate this during lunch and fight against my friends, one of them used to beat my ass as Strider. Good times!
It's fun going through arcade mode to get all the endings because you could always just play whatever team and in the final boss kys then switch to Mega Man + whatever character ending you want then use him to laser beam cheese and get the last hit with your latter character.
Also has some cool hidden characters like Roll which is always fun!