Ochu (or Oytugh :p) is a tool that adjusts things while you play. You can make yourself invincible, turn off random battles, speed up the game's frame-rate, and a bunch of other cool things.
I think another option is to find the old enemy editing tool called 'Hojo' and use it's mass-edit function to set all enemy HP (including bosses) to 1; that way you can just breeze through. Or for lv.99, you can use the Black Chocobo tool (or Steam's character booster) to set Cloud to Lv.99; everyone who joins the party from there will be Lv.99 as well, or close enough to it.