Rockman 6: Unique Harassment is a very hard and wellmade hack of Rockman 6 that came out last year. It features a lot of enemies and elements from other games in the series, along with multiphase robot master fights that are all tough as nails.
Link: https://www.romhacking.net/hacks/5179/
I actually had the first seven of these runs recorded shortly after the hack came out, but a combination of distractions and a certain boss delayed me from coming back and finishing the job for a while.
Not a single one of the robot master battles is easy, and they all have a number of attacks they use in a random sequence. After depleting one health bar, they go into a stronger and more dangerous phase making no damage buster runs all the more challenging. I guarantee they are all even harder than they look. Tomahawk man took way too many attempts.
Aside from the boss, the rest of the stage is pretty simple. Each of the 8 opening stages also feature a Doc battle empowered by another robot master ability from the series. This stage's Doc Magma can be cheap, but he's manageable with a little practice learning the correct movements. There are both easier and harder Doc fights ahead.
No save states or slowdown used.