Boss Theme Something to note about this game is that the sound of the boss's life bar filling interrupts the music, so you won't hear the part between roughly 0:03 and 0:06 during these fights. Every boss deals eight points of contact damage except for Pharaoh Man, who deals four. Also, since Mega Man has a charge shot he can now get hits in for three damage at a time, which is usually faster and easier than picking away at a boss with normal shots. This makes weapons less of an advantage overall, as the weakness damage is generally three or four.
At first, Ring Man feels similar to Quick or Needle, in the sense that he's throwing damage all over the place and you just have to take him out fast. He actually has a very simple pattern though. He throws one Ring Boomerang along the ground, jumps straight up and throws another as the first returns, then walks forward a certain amount and repeats.
How far he walks and throws rings depends on your distance from him. However, he'll throw a third if you shoot at him while he's walking, and this was a great idea on the designer's part. It throws the player off, making them think that he isn't as rigidly behaved as he is and causing them to panic. Taking the time to learn how he works is rewarding, and since the timing and method to dodging his rings changes with your distance, it remains fun even when you know what to do.
His weakness is the Pharaoh Shot. Taking hits won't interrupt a charge, so you're free to ignore him and win the damage race with this. Mega Man can start a charge while the health bar fills, and running into him while holding one counts as a hit, which can make the fight go even faster since you'll fire another charge when letting go of the button.
Dive Man is pretty disappointing as a water boss. He'll either rush toward the player or fire three homing missiles. The missiles appear at the right height to shoot them and Dive Man never leaves the ground, so just make short hops over him to ensure that you'll have time to jump again if he charges and to shoot down the missiles as they appear.
The only purpose the water serves is to dupe new players into making big jumps and letting the missiles chase them. He'd be alright as a starter boss, except that his contact damage is high enough to make the fight very difficult until the player learns how to dodge his charge. It's frustrating at first and boring after, and to cap it off, his main weakness (Skull Barrier) is difficult to hit with. Luckily, he also takes extra damage from Dust Crusher.
Skull Man can either fire three shots at Mega Man (he'll fire upward if you jump, but only at one of two set angles), jump, walk forward, or turn on his shield. When he uses the shield, he stands completely still and does absolutely nothing. Though it protects him from damage, the shield doesn't affect Mega Man, so the player can just use this as a good opportunity to jump over him.
Again, the real difficultly here is avoiding contact with Skull Man, though getting backed into a corner when he starts shooting is also likely. His weakness is the Dust Crusher and the Balloon can be helpful for getting over him, as Rush Coil and Wire take too long. He's got a little more to him than Dive Man, but the fact that he does nothing of interest with the shield is a huge let-down.
This is another fun one. Pharaoh Man jumps around the room, and can attack by throwing small shots in the air or charging a wider projectile from the ground. He's fairly active, but since he deals less contact damage and leaves himself open while charging, he's not particularly hard as long as the player is aggressive.
The terrain and lack of a set pattern keeps this fight interesting even after knowing what to do. Flash Stopper works against him, allowing the player to wear him down while he's helpless.
Bright Man either jumps toward Mega Man or fires three shots in a row. Unlike Skull Man, he always fires one upward, one downward, and one straight, though he picks the order randomly. This would be insultingly easy, except that he can also freeze Mega Man in place as Flash Man did. However, Bright Man can do whatever he wants afterward, and if he decides to jump he will hit you and it will hurt. The only good thing about this is that he doesn't seem willing to do it often, and I couldn't get him to use it at all until taking off around half his health.
Still, there's really nothing redeeming here and the potential forced damage is just frustrating. Mash Rain Flush at him and call it a day. Skull Barrier deals two damage to him, but it's dangerous and there's no point with charge shots available.
Toad Man jumps toward Mega Man when the player shoots at him, and does a little rain dance to damage the whole screen if left alone for a couple seconds. This might catch a player off guard once if they try to charge, but otherwise this fight boils down to shoot, move, repeat. Shoot with Drill Bombs to get it over with faster. The idea of being able to interrupt a dangerous attack is a good one, but this was not the way to implement it.
Drill Man dives underground and pops back up after a set time. Walking back and forth is enough to dodge this unless he catches the player at a corner, and Balloon or Wire can keep the player in the air until it's safe. Between dives, he can jump around the room or walk forward while firing missiles, which explode on walls or wherever he decides to detonate them.
Fighting him on the surface is frantic and works well, but he spends about four seconds underground each time and can dive again without giving the player much chance to hit him, so this can take a while. It's a decent fight, but it'd be a lot better if they had cut down the time he spends underground, or forced him to spend a certain amount of time above it between dives.
His weakness is the Dive Missile, which is useful for hitting him while he's jumping around. The missiles lose track of him as soon as he begins to dive, and I feel like they missed an opportunity here. Rain Flush can damage him while he's underground and it would have been neat if Dive Missile followed him down as well, though of course they would have had to make him move around in that case (if you turn off the background layer, you can see him sitting still until it's time for him to attack).
Dust Man jumps between the ends and middle of the room, slowly fires a block of junk, or tries to pull the player towards him. The blocks explode when they reach Mega Man's position at the time they were fired. Jumping straight up, sliding, or just walking away is enough to avoid these.
Once the player has that down, there's nothing to it beyond pumping damage into him and hoping he doesn't use the vacuum move much (not because it's any kind of threat, but because it wastes your time). This is very similar to Magnet Man, but Magnet at least tried a little harder to look exciting. Dust just feels like a lazier version of the same.
The boss selection is pretty mediocre this time around. Dust and Toad are trivially easy, Dive and Skull are dangerous for their contact damage but fairly boring otherwise, and Bright is a cheating bastard. Ring and Pharaoh are good and Drill is acceptable, but this is the first time we've had a mostly disappointing cast with a few standouts, rather than the opposite. They also have fewer secondary weaknesses than previous games, and the charge shot removes any reason to use them except in Dive Man's case, though I appreciate that the Wire and Balloon items get at least one reason to use them during a boss fight.
Not much else to say really.