I remember beating the festival coming out first by at least having the mythril dagger or the butterfly sword at lvl 6-8. Then you're all set. When you're sent to the theater district, fight the mu and bird in the first screen, fight the bird in the second screen (where your hideout is), and the wolf on the third screen.

Then rush back to the airbus and head to the shopping region (you should have spent about 4 min in the Theater District). Fight the mu and the bird in the place where you can enter the inn, fight the wolf on the left and head to the northwest. Fight the bird and the mu there, and head back. Help Vivi by killing the wolf, then head o the northeast. With Freya on your side, kill the beast but make sure Zidane makes the final blow. For it it would have to be 4 shots for Zidane, 2 jumps for Freya with Zidane's 4th blow the last.

Then head to the industrial area (you should have about 2 minutes left) and hit as much as you can. I'm not sure but once you defeat the beast, there's nobody that can stop you from winning.