The Teleport System was cleared already, therefore the Boss Rush takes place in the same fashion as in Mega Man X: throughout the final stage.
Stage segment
Robot Master
Walkthrough
In case you didn't recharge the weapons, this stage starts with three W-capsules.
The first sub-boss is Cold Man; he's weak against the Lightning Bolt.
The disappearing blocks in the first room have two different patterns: Bass can skip it with a double jump, but Mega Man must study them well before getting past; the Ice wall can help.
Astro Man is weak against the Magic Card.
The Metrengers (worms) allow to easily refill all weapons and energy. There's a spare body, but the Ice Wall or Treble Boost are required to reach it. Anyway, it allows for infinite retries against the next sub-boss.
Dynamo Man is weak against the Copy Vision.
The first Item Present is right after Dynamo Man, that indeed is known as a strong Robot Master.
Pirate Man is weak against the Wave Burner.
Use the Magic Card combined with the Super recover and collect the items.
Burner Man is weak against the Ice Wall.
Since Burner Man is another difficult Robot Master, here comes another Item Present. Before the next boss, though, you have to face Sisi Roll.
Magic Man is weak against the Tengu Blade.
There are two invisible pits before and after Sniper Joe. If you jump up the one on the right, then you can climb the ladder on the left and get Sniper Joe from behind.
Ground Man is weak against the Remote Mine.
Check the Boss section (below) and your menu before collecting this last W-capsule.
Tengu Man is weak against the Spread Drill.
(see boss below)
One last Item Present, just before the final boss.
BOSS: Dr. Wily
Like many elements of Mega Man & bass, the final boss, too, is inspired to Mega Man 8.
Screenshot
Walkthrough
Phase 1: WILY MACHINE 8-B The weak spot of the Wily Machine is the window where Wily is visible. Hit it with Remote Mines. You probably should better equip the Super Armor in the first part of this battle.
Phase 1: WILY CAPSULE 8-B
Equip the Lightning Bolt together with the Energy Saver: it deals just one damage, but it allows to dodge Wily's attacks. Mega Man can aso rely on Beat, after the Lightning Bolt runs out of energy.
When the Capsule appear near the ground, open the menu and equip the Magic Card and the Super Armor: the weapon deals good damage, but you need protection against Wily's attacks.
When you run low on energy, you might switch to the Counter-Attacker, but only when the capsule appears near the gorund.
