Bahamut Replace Doom Gaze/DeathGaze?

As Tenkraider is stating if you wanted to have an event occur before the battle it means you will need to modify more things in game, not the least of which will be making a custom event.

If you only have a few lines of text you want to use I would propose using the in battle text as soon as the fight begins. You won't be able to do much, but it might do essentially what you want.

If you don't mind telling us exactly what you want to achieve and how you wish to achieve it we can probably help you in making this happen. If you are looking to make a Bahamut fight more like FF5 your best option might even be to remove Doom Gaze (or just make him drop a different item/esper) and set up a custom event somewhere else (like on the ground) that can trigger the battle.

@Tin Man thank goodness that's the answer I want to hear it yes it is If I won't do the dialog for Bahamut then the only option is battle text in FF3UsME and yeah I need to modify the event of custom boss hack event.....If you asking me exactly what I want to achieve and how I wish to achieve as we know in W.O.R we encountered Doom Gaze/Death Gaze in random battle and we get The Bahamut esper upon defeat this creature and it so boring to fight Doom Gaze over and over until it dies.So all I want is to change the new event ala FF5 advance in different way but like you said need to modify more things in custom event, so I need help from the experts to making this happen.
The AI battle scripts, sprite image from this creature and the skill moves are ready but only problem is yeah the event but I won't delete the event for Doom Gaze as the replacement for Bahamut.As the battleground in the GBA/SNES version of FF5 usually Bahamut appear and fought in mountains(I don't know what is name) in Merged World, so I only think is either the clouds(AirForce's Battle in World of Balance), top of mountains(Various place) or both of them I can't decide.about the BGM I like theme of FF5 titled "Sealed Book" in replace for ff6's "Another World of Beasts" as change BGM cause I believe this is the same where bahamut appeared....So that's all I can say matee.....