Hey there. I've tried out Hardcore (non-Critical) and I've got a few things to say. So far I like the changes but there's a few things that bother me...
The enemy damage is a little too high. Seriously, EIGHT damage from a Fighter Fly? And then the bean enemy's Fake Out, as you described, does 21, with DEF levelled at least once on both chars. I understand this is meant to give me incentive to grind, but I think 4 to 6 would've been just fine for damage, starting out. But the way you see it, you didn't want to go easy even starting out (even though Bowser and Fawful are still pathetically easy, even with their HP increased)
When fighting Tolstar, the Bullet Bill is horizontally below Luigi, meaning while Mario has to dodge his, Luigi does not. (Also I don't know how much damage Tolstar hits for, because I actually Perfect'd him. DO NOT ASK how that happened because, honestly, I never have before because I suck.)
Is the name Critical derived from the Kingdom Hearts games? (Yes I am a fanboy of the series, shut up) In 2 you could equip an Ability called Zero EXP/EXP Zero which would prevent you from levelling up, but you still gained HP/MP after certain bosses (with Critical mode reducing the rate). As such I can't help but notice the similarity.
Also your YT link doesn't work anymore. Sorry to be two years late but I am legit interested in this hack.