What say you, Robot Masters?
I'm not trying to be an evil wraith guy that feeds off of your crushed hopes and dreams...but I don't really like the sound of this. Defend yourself.
Choice of robot enemies: mainly insects, dogs, spiders, bats, and aquatic critters. Mundane critters without any anime style to them.

Kindly explain what makes this ever-iconic mainstream MM enemy over-the-top and anime-like.
Original though slow moving robot master designs: At least in the first Mega Man DOS. I know that 3 ripped designs off the NES games, and all fought the same way.
Why would those sluggish moves ever be considered a good thing? Those bosses were so easy to mow down, it was laughable.
Since I do have a fondness for the old title and for Apogee/id DOS platformers, and since there was only a DOS 1 and 3, why not a Mega Man DOS 2? It would be perfect, because I could parody the style, look, and gameplay of Mega Man DOS, but at least make it more fun to play than the originals. I would try to make MM DOS 2 be to the MM DOS games what Mega Man 2 was to the Mega Man games.
So, combining MM2's objective overratedness and mediocre music with MMDOS's clunky physics, ugly look, and relative lack of difficulty? No, thanks.
The Robot Masters he faces are deliberately meant to be mundane and dull
Tell me you didn't just say "let's be boring on purpose..."
Robot Masters:
Globe Man: Spinning Globe Projectiles
Daimyo Man: Vibrating Katana Slash
Oven Man: Environmental Broil
TV Man: Static Interference Wave
Kraken Man: Feeding Tentacle Grapple
Vitamin Man: Pill Bomb
Computer Man: Error Screen Attack
Motorcycle Man: Gas Blower
Pool Man: Chlorine Grenade
Radioactive Man: Mini-Atom Bomb Blaster
Lawnmower Man: Mower Blade Projectile and Grass Thrower
Bookworm Man: Re-educator Annelids
...and with concepts like this? I've never heard of half the ideas in here being done by anyone, really. These Robot Masters deserve better than the DOS treatment; they deserve less generic looks, more engaging boss battles, weapons that are actually interesting! The DOS style has proven to have none of those, and making a game to be "like DOS" simply won't hold up.
At one moment in the game, Mega Man is kidnapped, and Roll must rescue him by becoming MEGA WOMAN, for at least two levels and then she's back to being Roll.
Why even bother? If "Mega Woman" doesn't have any unique gameplay attributes, then there's no point—aside from removing weapons from the player for a few rounds, which could be handled in other ways (See also: Shadow Rockman, Rockman 4 MI). If she does, then you're limiting the player's ability to have fun playing as her. What if I'd rather keep being Mega Woman?
In conclusion:
Basically, "ew, Mega Man DOS style." It has often been said that Mega Man should find a way forward in its fangames and stop banking on the same art style every time (Though admittedly I'm too lazy to learn a new style), but DOS sounds like two steps back. The existing DOS games have proven to be visually unappealing in all aspects; to have physics that are awkward clunky and certainly not what we're used to; and to simply be not as engaging or as fun as the real deal. They were hastily built to bank on the real Mega Man's popularity, and it shows. I cannot realistically see myself wanting to play a game like it.
Yeesss... CHAOS_FANTAZY, I do recall reading you're rather weird and reactionary rant on the Mega Man Unlimited forum about MMU's story and ending. I sensed that I might cross swords with you at some point once I posted my idiosyncratic fan game ideas here once I saw that you are a member here, so I'll try defend a few of my points as best I can.
When I said mundane, I didn't mean "boring." I meant anchored in recognizable settings that are slightly futuristic. I just got that vibe from the DOS version. I know I'm not making sense, so never mind.
I agree that Mega Man deserves more interesting, unique boss battles, with interesting weapons. I like you passion, and I would very much like to play a Mega Man fan game created by you if you ever develop it. I know that you are all about Mega Man games with awesome gameplay, bosses, writing, and story, and I hope you pull it off. And I want my intentionally generic named Robot Masters to also be unique and awesome too.... Okay, I want to make them slow as in Mega Man DOS, but I don't want to have them fight and move around the same way as DOS 1 and 3 did. As for the attacks for my basic RMs being uninteresting, what's so uninteresting about heating the entire level room to kill all enemies, or using giant squid feeding tentacles out of the Mega Buster to throw enemies behind you or grapple ceiling hooks, or using miniature atom bombs a la MDK 1 on selected targets or reinforced walls, or using a hand-held power katana to split robots in half (with a robot-splitting animation before they explode), or using rapid robot worms to force enemy robots to fight for you, and laying vitamin mines which once ingested by enemy robots cause them to expand and gibbing into useful power-ups? Well, of course I didn't specify how each of the attacks worked, so that was my fault.
I thought those attacks were at least unique. Maybe I should just change Globe Man's ability to a means of random teleportation, so that Mega Man would end up in a random secret area when he uses it during each level (like the teleporter gun from Half-Life: Opposing Force). Or at least summon a squad of geographer robots who fight like Captain Planet's team? Naw, just joking about that one.
I like that you like the idea of playing a Mega Woman. There could be an option where Mega Woman could be used to play the entire game. I was just thinking of intentionally making it a small level as a teaser for an actual Mega Woman fan game, because I think it's about damn time there was one. A whole game where Roll matures to Robot-Womanhood, battles a horde of Robot Mistresses, and deals with the female equivalent of Dr. Wily.... It's something to definitely consider.
And you think that MM2 is overrated and has mediocre music? Whoa, man, those are fighting words. I was thinking more in terms of adding more intensity to MM DOS like MM2 did for MM1. I'd like to know which MM game you like the most, and which MM style music you think is best. I could use your opinions for reference. I am surprised that you think that even Wily stage music of MM2 counts as mediocre. You didn't have a personal falling out with MM2 at some point, did you?
OK, and I admit that I liked MM DOS for its lack of NES level of difficulty. I am a heretic. Execute me on the altar of Guts Man if that will make you happy (or to whatever Robot Master you think is superior to Guts Man). I haven't learned to be adept at playing Mega Man NES just yet, I definitely should. And I don't want my MMDOS2 to be a repeat of the difficulty of MMDOS1, nor to confusing level design of MMDOS3. I do want it to be difficult, have easier controls, original textures, at least imaginative and fun level design, and some additions for the NES MM games. I do like the slow gameplay, though I do recall that the speed could be regulated to be either super slow or super fast in the DOS versions. I could put in a more manageable version of that feature in.
And I didn't say that the creatures from MM NES were over-the-top. I don't know why you don't see that the MM NES and others are done in anime-style, because they do. And I like minimal anime style in those games. I just find it interesting that the MM DOS games chose to go against that style, and mainly used critters that just look like average animals without any expressive faces (except for those little helmet guys which have a short cameo at the end of DOS 1). I still can't get over that MM 3 had nautilus and shell-squid robot enemies in the Shark Man stage, or had Mega Man swim endlessly throughout a dark oceanic level with confusing design.
All in all, even if you can't see yourself playing such a game, rest assured: you're not my target audience. You don't have to play it even if I could pull it off. I don't want to make the same mistakes as the MM DOS creators when it came to design and texturing. I agree with you that they were hastily made. Capcom should have commissioned id Software to make a successful port. At least id put effort into making a smooth-scrolling platforming experience, and they even pulled it off with by trying to port Super Mario 3 to PC, and asked Nintendo if they were interested (the port resulted in the demo Dangerous Dave in Copyright Infringement). I discovered from a video playthrough of MM DOS that it started off as a fan game that Capcom endorsed, which means that id could have easily had more success with Capcom than Nintendo. Apogee would've at least made a better MM DOS game (sigh).
Anyway, I don't want to reuse the old textures from MM DOS or NES games. I want to make my own. And of course, I'd want the Robot Masters to have better animations than those in the DOS series. First, I'd need to find a game designer that would enable me to replicate pixel and gameplay style of my favorite DOS platformers, such as Duke Nukem 1 and Secret Agent, and those of the inferior games like MM DOS. Game Maker might do, but I'm wondering if there is some other kind of game designer that would make my ideal retro-platformers really retro as I know them. Overall, this is a combination of DOS and NES games I might use for inspiration for the game's look and feel.
Mega Man 1 (NES)
Mega Man 2 (NES)
Commander Keen 1-3
Duke Nukem 1
Super Solvers: Challenge of Ancient Empires
Mega Man DOS (just for basic aesthetics)
Mega Man DOS (to a very small extent. maybe remake the levels for Oil Man, Shark Man, and Torch Man)
Mega Man X (for secret level)
(EDIT: I might even use Mega Man 4 and 6 for inspiration)
Plus, I'd want to incorporate some laid-back exploratory levels. Like, you can go back to Dr. Light's base and explore in inside and outside, search for secret areas, and interact with other characters without fighting. Dr. Light would have a training room, lounge room, various bedrooms and bathrooms, a shop, the basement where Protoman is living in for rent while finding a place of his own, and a nice hiking park outside. Players could put RM fighting on hold just to hang around the place.
As I said, I'd like to find the right kind of game designing tool to get the kind of retro fangame that I'm after.