Mystic > ssj 3 and can be maintained
There is really 1 main difference between young gohan and teen gohan....
Young Gohan is psychotic
No joke. His dad was murdered in front of his impressionable eyes, his best friend and most his other friends were murdered in front of him, his remaining friends were killed later on, his dad left and didnt return for several years because he didnt "feel like it", the entire world was against him and his remaining friends gone, his father returned only to be killed again, while still a child he held the fate of the world in his hands several times over.
Come on, why does gohan explode as a child? He's flippin insane, thats why. If you gave that last paragraph to a psychiatrist, they'd say.....Woah...got me....if I was that kid, i'd be nuts too...
At times young gohan is down-right frightening. Look at the clips of when he attacks raditz, Dr Willow, Freeza, Garlic Jr, the spice boys, cell, when he almost goes ssj in hyp time chamber, when he fights bojack, when 16 dies. Want the worst scene of all? When he is in the hyp time chamber and he gets beatdown and goku powersdown and walks away and he looks back at gohan, and gohan looks up at him with angry eyes and an evil smile in his face. That face just screams "I want to kill you and drink your blood".
Teen gohan had enough time to "forget" about what all had happened to him as a child.
Teen gohan does become far stronger than any other fighter in DBZ once he goes mystic. Not only is he stronger than Goku ssj3, but he can also maintain it, forever.
The only reason ANY fighter is even comparable to Gohan at the end of DBZ and DBGT is that Gohan....is not a jock. You have Vegeta and Goku runnin around like rocks, doing nothing but exercising for like 30 years, and Gohan is still close to the same level as them or on a greater one. Had Gohan the "urge" to fight and didnt care about providing for his family, he would have been stronger than a ssj6 in equivilance at the end of DBGT.
There are really 4 logical choices to chose from...
Have young gohan only
Have teen gohan only
Have both
Have both within one class
Young Gohan only would be-
Normal<ssj<ssj2
This form would have "psychotic features makin him worth playing"
Teen Gohan only would be-
Normal<ssj<ssj2<Mystic
First and last would basically be the same, but with diff clothes
Have both would be-
Both the previous
Have both within one class would be-
Young Gohan<Young ssj<Young ssj2<Teen ssj2 (optional)with the vs buu clothes<Mystic
The transform between young-teen would be an age-morphing transformation
+ of this is that the first 2 models are already made and arnt wasted