Few Questions

I don't know of any Esper-exclusion patchs or patches for editing without learning and digging into the hex coding and doing it all yourself.

What you could do is have character-specific items teach spells and limit the Espers to spells you wouldn't mind everyone learning or having the Espers themselves act as a "one cast per battle" kind of spell that teach none of the spells and/or just offer the level-up bonuses.