My thoughts:
MM1 classes: Y U NO MMPU TAUNTS. Oil Man is ok (I like him, actually), but it's kinda disappointing to just depend on your primary to attack with your oil shots and ramming, so I suggest making Oil Man able to jump out of (not like what M1 does, but just a small jump) his Oil Slider as a projectile with M2. Also, allow him to slide over water with his Oil Slider as well. Time Man is ok, but I think Time Slow can be a bit abusable.
MM2 classes: Once again, you're forcing Quick Man to always be quick as hell. I propose making him just slighty faster than other classes while still technically keeping him the fastest, and make his superspeed an item ability with an ammo bar that refills over time. Heat Man's Heat Dash still consumes way too little ammo IMO. The rest is ok.
MM3 classes: Although Spark Man is not OP anymore, I feel it's not as fun as it was back when he was OP. Gemini Man's Gemini clone needs to die whenever the original Gemini dies, so it can prevent clone traps and clone armies. Snake Man's climbing HUD still has some graphical problems (white pixels left over in the animation). People got a bit picky when they found out Needle Man now has a spinup time for his Needle Cannon, but I think it's ok. The rest is ok.
MM4 classes: Bright Man still needs a slight buff IMO. Ring Man's Ring Boomerang seems to be a bit propense to glitch out, so why not just giving him the original Ring Boomerang and be done with it?. The rest is probably ok.
MM5 classes: It's probably ok. NESPalm Man isn't really necessary, though. Star Man is now exactly what it's supposed to be: a ramming class.
MM6 classes: I haven't really checked enough, but is Knight Man's shield dash supposed to do any damage?. It's also nice to see Centaur Man depend on his buster more than his Centaur Flash (why not replacing his buster with Centaur Arrow?). The rest is ok.
MM7 classes (hoo boy):
-Freeze Man could use an extra ability with M2. Maybe a charge shot that freezes people?. Ice spikes are fine and all, but shouldn't that be Chill Man's main ability instead of Freeze Man's?. REPLACE TAUNT WITH SOMETHING ELSE.
-Slash Man is basically a Demoknight. I don't see any problem with the main concept of it, except for the already mentioned dash bug.
-Spring Man is cool and all. BTW, Spring Punch actually does damage (I killed a Knight Man with it). FIND DUKE NUKEM FOREVER VOICE CLIPS AND REPLACE CURRENT TAUNT WITH HIGHER QUALITY VERSION IF IT EXISTS.
-Shade Man is cool and all, but his M2 doesn't seem to work properly on water (tried in Ice Man's Stage, couldn't fly out of the water). ADD BELA LUGOSI TAUNT.
-Turbo Man seems ok for me. I recall some people calling it OP, but I didn't grasp how it was, actually.
-Burst Man is ok. It's actually a fine replacement after Crash Man's ammo nerf :,<
-Cloud Man is ok as well. Very ingenious of you to make him able to manually recharge his ammo.
-JUNK MAN IS GRIEFING MATERIAL, AND CAN MAKE A MATCH VERY LAGGY IF USED TOO MUCH. Too many scrap pieces flying around the place. Either increase scrap drops after other classes die, or decrease the amount of scrap metal Junk Man can leave around the place. JUNK BLOCKS NEED TO BE ELECTRIFIED WHILE IN PLACE TO SYMBOLIZE THE DANGER OF APPROACHING IT. I also thought at first that you could punch it and use it as a projectile at first. How about clicking M1 once to summon the block attached to your claw (should not be able to move while holding the block), then either clicking M2 to punch it forward and use it as a projectile OR clicking M1 again to place it in front of you?. More importantly, it's enough for Junk Man to have both his Junk Shot and Junk Shield, so why was the Junk Block added in the first place AND AS HIS PRIMARY?. DO NOT TAUNT THE CLAW.
TL;DR, Oil could use an alt, Quick's speed should be controlled through an ammo bar, Gemini clone needs to die when Gemini Man dies, Bright needs a slight buff IMO, Freeze could use an alt. charge shot that freezes people, Shade's M2 needs to work properly on water or just don't work at all, Junk Man leaves too much junk all over the place and his Junk Blocks need to be more useful and less OP or just rid of it entirely (being electrified to show danger, being able to use it as an attack).