Yeah, I just started playing 5 for the first time and once I realized you could combine classes I went into super nerd mode and my team ended up so hardcore that even bosses are a three-turn joke. I think my favorite is the Berserker with the passive two-handed axe weilding, which does about 800 damage.
But overpowered as hell is the only way to play through any of the Final Fantasies. Which is also why I like 8. I always go completely apeshit with the Junction system and get 9999 health for everyone by Disc 2