I am interested in seeing this get picked up again. I'm pretty much in agreement with Medal and Badz, as they summed up the general gameplay tweaks better than I could. But I do have some personal opinions on each of the bosses.
Bosses I want back:
Saxton Hale: Saxton is pretty basic and I wouldn't change too much about him as he stands now. I like the idea of a battle roar that stuns nearby enemies. It could make his rage a little more useful when used together. I think.
Ghost of Starman: I don't think there's anything else you can do for this guy. He's good, and he should come back. It's kinda difficult to control his star attack, but in the right hands he is a monster.
Cave Johnson: Keep.
Gilgamesh: As much as I like Gilgamesh, he's very luck-based with his main attack and that's lead to a fair amount of raging. You have someone right where you want them, and *Dink* goes the Excalipoor's chip damage. On the other hand, I've been OHKO'd by his lightning from standing behind him, thinking I can get the jump on him while his focus is on someone else.
I don't think his main method of attacking should be so randomized. I know you guys wanted to have his multiple swords and all but surely there's another way to handle it?
Scrooge McDuck: I love this guy, but sometimes Scrooge just seems a little TOO powerful. He's the type of person who just stays on your (duck) tail, whacking you in the butt with a cane and you just can't shake him off. I've been on both the giving and receiving end of this. Scrooge is fast, his re-fire rate is one of the best out of all the bosses, and essentially has a room-clearing rage. Balance might have to be looked at.
Dio Flash: The only thing I would ever change about Dio right now is fitting him as a secret boss. I feel he's too special to be on the same level as mudkip or morshu, or most anyone else in the regulars. :V
Ra Thor - SAR: I'm guessing this is the one with the different types of projectiles? Yeah he was interesting, but I don't know how he'd fair on his own.
Super Macho Man: I feel some tweaks to his attack hitboxes are in order. I find it very difficult to hit anyone unless I'm right up on them, despite how ridiculously far Macho Man throws himself with each punch. Perhaps the farther away the opponent, the less damage and stun/knockback they'll take?
Quote and Curly Brace: I do like these two and the separate roles they play as a team, but again, balance should be looked at. As far as I know, in the version of SH that's been played recently, Quote's main, uncharged fire does a lot more damage than it probably should. You can also fire it at a decent rate, making the charges almost obsolete.
Genesis Unit: Aside from PO'd Roll and Ra Thor(s), these are our only megaman bosses! They gotta come back. I wouldn't mind seeing some changes made to them, maybe try to squeeze in some more abilities from their campaign battles? (i.e HSH's charge) I feel like in general, Buster Rod G is the only one who's actually dangerous, despite the fact that he always dies first! Admittedly we've been playing in a version where HSH's inhale is broke...
Unknown Robot Master: I liked this guy. He's kinda strategic with his flunkies. My only real complaint is the ludicrous HP on all his enemies. The hp on minions need to scale with the amount of players, much like the bosses do.
Tomahawk Talbain: The darkness gimmick gets on everyone's nerves and you all know it. That aside, he is very fun to play.
Gouki/Akuma: Dude I can't even give a proper judgement on this boss because I only ever fought him once--on the day he was made and released. All I can say about him is make his appearance time more reasonable. There is literally no reason to have a boss that's borderline impossible to reach without some sort of console command.
Captain Falcon: At this point don't count on me remaking his moveset. Instead, do you remember the Saxton Hale Classes mod? Captain Falcon in that worked close enough to what I'd envisioned. If you guys can get him to work more like that, then he'll be great. I may even continue spriting him to fit all his needs.
Bosses I'm on the fence with:
Ninja Spy: I'm very meh about ninja spy. He has "lives", but taking one down really doesn't feel like you actually killed him at all. My suggestion for this is to have him automatically respawn (like exit unit) while leaving behind a death explosion effect.
GutsManG: Interesting concept. You say you wanted to make him fundamentally opposite of slender, right? Well, ya did. But I'm not sure you planned to have the negative aspects go in reverse as well. With Slenderman, everyone is running/camping or otherwise trying to keep away until time runs out. With Gutsman G, It's the boss that's running/camping or otherwise trying to keep away until the time runs out. They're both still incredibly campy bosses no matter how you turn em.
Mudkip: Really don't care much for the guy. I mean, he's kinda okay and unique, but meh.
Torchic is a butt.
Seemen: If you rework these two to be a little different from Saxton himself, maybe make them both unique from each other (kinda like the Quote and Curly dynamic,) these guys could be interesting. As they stand now, the only thing I really care about is their heavy metal theme song.
Remilia Scarlet: As mentioned before, Remilia has SO MUCH potential here that isn't being used. As she stands now, she's too weak to do crap until her rage kicks in, in which she's too OP to keep around. The balance here is non-existent.
Bosses I really don't want back.
Morshu: get out morshu He started off as a literal recolor of one of my least favorite YD classes (at the time) with the persona of a living meme that got old decades ago. I'm honestly against having memes like this in the mod at all, and I feel we could do without them just fine. Personal bias aside, his tools make him interesting but his controls are too clunky to really be effective. he's also too slow to be an effective suicide bomber and that's a bad
Pissed Off Roll: Roll kinda stood out amongst the bosses with melee attacks. She is a pain in the butt to fight and she heals in her rage. She's fast and she literally knocks people around the stage. I never really cared much for this boss; she just kinda feels shoehorned in to me, but that's just me.
Gamma's Feet: wat
Christian Brutal Sniper: I always found this guy to be a cheap pain in the neck. A rage that gives him multiple instagib long-range shots, that he can save for later no less, really kills the flow of the gameplay to me. If he can just whip out a death arrow outta nowhere because of a rage he had five minutes ago, it's not hard to catch anyone off guard. Take that away and he's really just ninja spy without an extra life or invisibility.
Slenderman: Do I REALLY have to go into this? Few people actually like this boss. I've suggested some alternatives in the past, such as the Ultimate Chimera, but overall the gimmick of running away from the boss instead of fighting it hasn't shown to be very good.
Though you're probably not gonna wanna look into new bosses anytime soon, I've still got my list of ideas if you're interested.