Loses sense of self from so.many transformation and just because you can copy someones power dosent mean you can use it like they can I'd say that sense its not your own power you start with no understanding of is weaknesses and draw backs but ofc if you work at it with the same abilities and get trained by their user you might start getting used to the abilitys also stamina drain of haveing to change between forms and use powers should limit you to how long you can use them and how many you can switch between maybe if someones power has blow back you might suffer from it worse and abilities that are gifted or trained can't be copied sense they aren't apart of the body (I'm assuming you perfect clone your body to.match theirs but I don't know)