Dr. Wily. This guy doesn't know when to quit. Oh well. It's time to take him out yet again.
Hard Hats are the biggest threat in this level. You know these guys, they're in every classic series Mega Man game. Just hit them when they're vulnerable and move on. For a watery section, you'll be able to use the Rush Marine, one of the few times in the game it can actually be used for something. However, ONLY use the Rush Marine in situations where you have room to manuver. Spikes are instant death even in the Rush Marine, and it's larger and bulkier than Mega Man in his normal form. In other challenging sections, use Rush and the other transport items.
At the end of the stage, you'll meet a giant Hard Hat. Not even a stage filled with the smaller variety could prepare you for this big guy. Don't worry, he's not all that strong. When he shows himself, hit him with the Ring Boomerang. But be careful! He jumps and tries to crush you, and when he hits the ground, four smaller Hard Hats will fall. You'll want to end this fight as quickly and painlessly as possible, so use the Ring Boomerangs to bring the pain. Your best bet for dodging him is to just plain stay out of his way and jump when he comes down, as his seismic attack can immobilize you. It's tempting to try sliding, but don't. It just makes you an easy target.