"FF6 T-Edition EX X.X.X.ips" is essentially bonus content and other things that were not able to be put into the main mod of the game, mainly due to the upper limit of boss monster battles able to be added, even with ROM expansion. Basically these are extra battles with various bosses from other Final Fantasy games. I put in the BGM for the "Soul Shrine" bosses, however, for personal reasons, I wanted to battle them with other BGM. I'm sorry.
FF6 T-Edition EX is only for fighting specific enemies and you can not play FF6 on here normally. This is because various game data (enemies, magic, battle content, battle backgrounds, maps, various flags, etc) have been changed and moved around to allow for this mod. Due to this you can only play with a saved game specially made in the main game in a certain Save Point location and then loaded here. If you attempt this please take caution as enemies are very challenging and your progress may be impossible based on your current strength/skill.