Now that most of the negative feedback is out of the way, I'm gonna be a little more positive.
Running feels slippery because everyone is fast. If you can't use a negative dvx to fix that, then don't worry about. It's minor.
I also tested Naruto and Goku, and I had no general problems with them. SSJ Goku seems negligibly slower in terms of attacks, but the more I look into it he isn't that unbalanced compared to his normal self. If he were to be a standalone I'd simply give him normal Goku's mobility. Normal Goku has more options overall, but SSJ's boosted damages (aside from Meteor Crash) kinda make up for it. Kaioken Rampage is a little awkward in that it doesn't hit consistently. For using 250 MP it really should be a lot more useful. Also, Normal has the godlike D^A.
Naruto's clones may be a little troublesome. As I stated yesterday both utilizing and countering such play is extremely MP-consuming on both ends. His Jump Attack shouldn't gimp his jump, or at least feel like that. See what happens when you adjust the centery to line up better. The attack is very good because he can cover more ground as well as attack low enough. I find it annoying that he can simply avoid every attack and is practically impossible to pin down. I'd place the ability either in the end of the hurt frames, or only during his dizzy, and PLEASE increase the MP cost to make players be more considerate of escaping. The same applies for Sasuke.
I was never a fan of Sasuke when he grew older. He became different in a way that was more drastic than everyone else. His design here is a bit more likeable to me. First of all, Chidori Stream has an offcenter in the end. The damage and MP cost is fine. His electric projectiles appear to be late-game keepaway with how little they do for a relatively hefty cost. Chidori Sword is also useless. I think all the hits should be knockdown with how little damage it does. The rest of him seems solid, becoming a healthy contrast from Naruto.
Luffy seems to be a little lost. He has a lot of good things going for him, but his movements don't feel fluid, especially Bazooka. Fluidity from movement is a difficult task. The last attack (Daihoru?) does multiple hits in the corner that seems unintentional. Make it vrest and increase the value to where it doesn't hit as often. It's extremely deadly. I can see Luffy being a good mid-range fighter that hits hard. He doesn't need to be fast or have a projectile as long as he has good damage output.
Gon is probably the worst character so far. He feels rushed and not well-thought-out at all. Gon's D^AA combo does not link unless spaced far away. His DvA does not follow into anything and leaves you open for punishment due to its recovery. Lower the dvx on the move so it can at least follow up with D^A for safety. You should also increase the dvx for the initial knockdown hit so the rest of the hits can follow up better. He can jump after hitting with a dash attack; pretty sure that isn't intended. Gon soars if you hold attack when you dash. Gon's DJA charge up allows him to charge past 500 MP. Why is it different from the other characters anyway? DvJ is a useless move. It does absolutely nothing for the damage and MP it has; it doesn't even knock down the opponent. I'll worry about his Jankenpo moves after seeing his fishing rod work properly.
The game seems to not be balanced in terms of early and late game. You have early-game options, and more options open up late-game. The problem is that some early-game options become overpowering because of increased MP regen and their now-negligible low MP cost. Aside from increasing the MP costs of options that become spammy, you can take a few pages from my book and alter the MP regen to take out 1 and 5 and boost MP every 200 HP. I'd like to look into making players start with 500 MP but there are so many 0C8 values...
Edward and Gon are the two characters I feel are underpowered for different reasons. One for the lack of moves, and the other for having moves that don't even work.
I don't think anybody feels extremely overpowered save for the things I feel need to be toned down. If anything, Hibari is probably the most overpowered because of that one single move that deals so much damage and shuts out so many approach options. Only Naruto and Sasuke could stand a chance because they can escape after the first hit and end up in a favorable position, and the ability to freely substitute is busted in itself.