>>18535617Mewtwo EX WAS the first EX pokemon (along with the 3 dragons), and he was an 80 dollar card at the time of release.
And no, X-Ball wasn't exactly unprecedented. Cobalion was carrying a similar effect before him. What made mewtwo's crazy was that it also counted his energy, meaning loading him up let him do more damage, something previously impossible using that class of move.