Most of the characters in Mega Man games are either stationary or on a continuous loop. You’re not really waiting for the characters to appear on screen before they start moving.
When I was creating Super Mario Bothers, I had to add code that would prevent certain goombas or koopas from moving until the board had reached a certain X coordinate. It’s a lot easier to just create the behaviors for an enemy and release them upon your virtual landscape than it is to make them listen for a specific trigger before activating.
I really need to get back into programming some more games and such. I mean, I do front end development for a living. So technically, I “am” programming all the time. I’m just talking about getting back into some of the meater languages that require more left brain activity. Nonetheless, thanks for humoring me during this little rant.