Just going by boss weaknesses, we should actually go to Slash Man's stage next, but Turbo Man isn't that tough with the Mega Buster, and his weapon is useful for finding a secret in Slash Man's stage, and there's some good stuff hidden in this stage anyway, so for the sake of minimizing backtracking, we're going to go here first. If you don't mind backtracking, though, you can go to Slash Man's stage next instead. It's up to you. Turbo Man's stage is in the lower left corner.
Right off the bat, you'll encounter a vehicle with a spiked plate on the front. You'll have to run, but you can also destroy it by shooting the driver enough times. Alternate between shooting the driver and destroying the weak wheel enemies in your path. You should be able to destroy the vehicle before the next area. If not, it will damage you and you'll end up on the left side of it to finish it off.
Beware these cones. They leap into the air and fire shots that spread out. The shots will miss you if you're standing close enough from their standing position. They can only be damaged while they're in the air. Take them out and climb the ladder.
Watch out for these tires. They'll bounce you away if you hit them. Also watch out for the spikes. They'll kill you, as always. Take out the traffic cone enemies as you make your way to the right.
This stack of tires is a trap. If you fall through the middle, you'll have to fight another bulldozer and you'll end up back where you encountered the cone enemies. Jump over it. There's an enemy here that is hiding in a stack of smaller tires. It will throw them at you. You can destroy the tires with your weapon, or avoid them. They move along the ground and are easy to jump over.
Destroy the enemy on the traffic lights, then make your way over to the traffic lights with either Super Adaptor or Rush Jet. Use Rush Search here to get the valuable Hyper Rocket Buster! This will increase the range of the Super Adaptor's rocket fist attack, and give it homing properties to boot. Get back on the ladder and keep climbing.
Continue up the ladder and hop off into the wall on the right. There's an area here you can pass through to reach a secret room, where you'll find Proto Man again. He'll just offer you some advice you don't need about the Super Adaptor, but you need to do this to accomplish something later. When you're done, head back and up the ladder, and then up two more ladders.
You can use the Freeze Cracker to freeze these jets of fire. Don't ask how that works. Frozen fire jets can be walked on safely, but you're not totally safe in this area yet. The jets will fire when all three lights on them are full. If you freeze a lower jet and one of the ones on the ceiling, you might block your own path, so watch out. Time your slide through the narrow space well. You don't want to slide into a jet. Make your way across and into the next area.
Are you getting Vietnam-style flashbacks of Quick Man's stage from Mega Man 2? There's a 1up and an E-Tank here, but you're very likely to die if you try to reach them. Those jets of fire are serious business and will destroy you with one hit. Make your way down through these next few areas as quickly as you can. Make sure you're not wearing the Super Adaptor here. Fall just left of the first platform. Immediately slide to the right and hold left to drop off the next platform. Hold or slide left to drop off the small centre platforms and quickly slide under the platform with the E-Tank on it. (Don't try to collect it. It's a trap.)
Now you'll be outside. Go right along the truck bed, destroying the weak flying enemies. When you reach the front of the truck, switch to the Thunder Bolt and shoot it in the eyes from where you're standing. Avoid the missiles that will come flying at you. The truck will die after enough hits. Hop off and head right.
There are some weak flying and wheel enemies in your way, so deal with them. Now it's time for the boss.
NEXT: Slash Man