>>718156643 (OP)
PSP remake has more content, including beautiful CGI celshaded cutscenes, but it has slowdown when special moves go off. The mobile iPhone version is the PSP one without the slowdown. The translations are different in both of them, the PSP version (iPhone, PSP) also removed the flavor text when a spells is cast. That's about it.
The upcoming $60 remaster is the PS1 version so you lose access to all those CGI celshaded cutscenes in favor of the original 1990s cutscenes.