Except for FFIV who's battle system was so stupidly broken that the only way TO WIN was to grind.
Odin couldn't even kill the standard moon enemies. What a fucking waste.
I remember playing it on the SNES and found myself going "Oh FUCK ME" near the end of the game when I found out every time I ran, It added EXP to the amount I need to level up, making leveling up hard, but thats because I was stupid and ran away from most battles because I really didn't feel like fighting. The I played it again with minimal running and found myself needing much less EXP to level up.
I.E. First time I played it I need like a million EXP to get to Lv 40.
Second time I only needed like 60,000.
Don't know if it was a glitch or anything but it really fucking sucked.
omega mk 12 was pretty fucking badass. he didn't have a lot of hp but his SUPER HASTE or whatever that cause him to constantly be attacking was pretty bad. I died against him several times before finally getting it.
which didn't help because the great crystal is quite possibly the WORST FUCKING DUNGEON EVER and when you lose... well. 
God I hated that Dungeon SOOO MUCH! Not to mention they crippled Omega Mk 12 in the US version, and hes still fucking hard as hell.