Because of the sprite limit of the early era games, its hard to say who is fat in FF1-6. I tend to think though that Gogo is a chubby guy/girl/thing. It doesn't make sense that its all clothes.

I know you've got a vendetta against the Cids, but Cid from FF3 DEFINITELY counts as overweight. In the remake of FF3 for DS he's a old chubby guy.

Cindy, one of the three Magus sisters who appears in at least 2 of the games is quite a fatty. In case you didn't play IV, she's the fat one in the Three Sisters summon in FFX.

Also, its Queen Brahne, not Brahme. Although Brahme is humorous because she is rather cow-like.

Also, compared to some of the stick figures in the series like Yuna, Rikku, Tifa and Yuffie, Lulu from FFX is "overweight" but to be honest I find her one of the more attractive gals in the series because she's realistically proportioned.