Patch for making Espers unique to different PCs?

Hi, I've seen at least one big gameplay overhaul (Brave New World) that implements this, however the IPS patch for that obviously changes much more about the game than I intend.

I'm wondering if anyone has access to or any knowledge of a patch. What I have in mind is a patch that ONLY will make certain Espers able to be equipped exclusively to certain playable characters. For example, Phoenix being only available to Locke and Terra, or Maduin only being able to be equipped on Terra and Strago.

This is coming from a person who has no knowledge at all of how to create or change a patch or how to alter code. Merely easy access to IPS files and FF3usME.