Maybe the injection that was given to Eren had some Senju oops excuse me , Ape DNA & gave him that power . We need to get to that damn basement .You guys could be right but i still thinking about that possibility because neither of the special titans( humans that can go into titan mode that we know) doesn't have the same special ability for example, annie, She can selectively harden parts of her skin to protect it from damage or to enhance her offensive strikes, it looks like ice to me? U_U IDK.
Ape titan and eren's titan have something in common.