Although it's interesting to have unique traits or abilities for each and every character. This sort of thing wouldn't balance out too well. You can bet that some traits would be better than another characters, and so certain characters would see less play. I'd rather that the characters got more balanced, not more unbalanced
i believe that since a stamina system has been added its possible to balance specials. stuff like kaioken and rage will take massive stamina to use. some specials will take health, immense ki, or a certain form. EDIT:infact ill list all the drawbacks
Goku - kaioken - uses immense stamina to hold (25 stamina/second?), as well as normal swoop drain (at a certain stamina/ki point it ends, same button that activates it deactivates it)
Gohan - extreme power (rage, works like kaioken/ all forms) - uses immense stamina to hold (same with kaioken)
Krillin - splitting discs - disc already takes alot of ki for krillin, to split them it takes even more (maybe only possible in super krillin form?)
Vegeta - majin, only as ssj2, it gives more ki and a new attack with the old attacks power raised - lowers defense, raises attack, stamina drains faster when teleporting, etc. beams take longer to charge and use stamina but are alot more powerful as well as adding the attack "atomic blast" if that what its called (normal ssj2 ki drain)
Cell - immunity from certain attacks like lasers and discs - getting hit by discs severely drains stamina, lasers a little bit, when stamina is below 50 cannot retain immunity
Ginyu - body change - powerlevel is severely lowered and slowly (very slowly raised when stealing a form)
Android 18 - fast energy gain - not really unbalanced...
Frieza - human telekinesis (chargeable)- takes alot of ki and slowly drains stamina, opponent can fight back to take more stamina/ki away while charging
Buu - ability to control body - uses stamina to maintain and very good timing (the attack deforms buus body to dodge attacks and beams
Trunks - Ussj2 - ussj2 is severely slow (in fighting and charging attacks), and takes a ki drain but offers extreme ammounts of power, uses alot of stamina to use powerful beams since there is so much energy to buildup
buu is the only one i really dont know what to give, the body ability is balanced but hard to put into the game
just checked a fan site (i never trust those things)