possible improvments that can be made to boost the character's potential without overpowering him.
1: teleport should not take 8 frames to have active invulnerability frames. Cut that in half to 4 frames.
2: should be at least samus's weight, floatiness should remain the same
3: remove at least one of the hurtboxes on his tail
4: change the properties of disable and confusion (taj has covered this several times and we both fully agree with his opinions, such as confusion REflecting projectiles and forcing opponents to tech when you catch them in it on the ground (maybe), and disable being able to sheild stab)
5: give the fully charged Shadowball a longer range
6: boost the knockback on the dair slightly
7: increase usmash and dsmash's damage output by at least 5%
8: mewtwo's fsmash already has a tipper with the exact same damage output as marth's percentwise. Now give the sweet spot similar payoff (ie knockback) to marth's - a dependable kill move
with these alterations mewtwo would be much more formidable (fitting the character better)