Looking through my model viewer there's a good handful of spells in the dats but simply never got put into the game (at least not for players). Here are some examples:
Libra
Toad
Tier 2 bar-spells
Invisibra
Sneakra
Tier 2 En-spells
Tier 5 nukes
Gravity 2
Comet
Meteor
Aspir 2
Break
Virus
Curse
Berserk
Confuse
The rest are simply ridiculously higher tiers of spells like Poison, Bio, Dia, aga spells and whatnot.