Boss - Junk Man
junk Man has some long annoying patterns. If you let him get into them, he can generate lag and have long invincibility. Fortunately, he also has a huge flinch animation to Thunder strike, which can trivialize the fight.
You should always enter this room with T. Strike equipped.
The Flinch Animation
Junk mam pops into the air when damaged by Thunder Strike. After landing, he jumps to the opposite side of the room, throwing a block of junk at you from mid-air. After landing, his attack sequence resets. His invincibility frames wear off about 90% of the way through the jump.
Simple Safe Strat
Open by shooting Junk Man with T-Strike. Junk Man will pop into the air (as described in Flinch Animation). Stand on the opposite side of the room, slide under his jump to dodge the attack, then repeat. Seven hits, and it's over.
Faster Strat
The premise of the faster strat is that there is a small window where you can hit Junk Man while he is still in i-frames, but the Split shots of T-Strike will hit him. This DOES NOT trigger the flinch animation, which while nice and easy to dodge, is slow.
You want to jump and shoot at the same time coming out of your slide under Junk, staying close to him.
You want to hit Junk twice like this on the left, not triggering the flinch. DO TRIGGER IT on the third hit - if you do not reset Junk Man's pattern, he will enter an invincible attack sequence. High jump on the third hit too, since Junk is about to slam the floor stunning Mega Man.
Once he is on the other side of the room again, repeat hitting him three times without triggering i-frames. Note the 3rd of these is the 7th hit that will end the fight.
If at any point of this sequence you send Junk into a flinch animation, don't worry. You can resume the strat on either side having only lost time. Missing the hit is effectively falling back to the safe strat.