Not sure if it's what you're looking for, but there IS a hack that allows monsters to use all 4 moves without Monster Skill.
Code Select
<Patch name="All monsters can use 4 moves (v3).">
<Location file="BATTLE_BIN" offset="11B634">
01000234
</Location>
<Location file="BATTLE_BIN" offset="133960">
00000000
00000000
00000000
00000000
00000000
00000000
</Location>
</Patch>