Here are just a few reasons why Yuffie is more groovy than any other FFVII Character:

1: One word: Gawd! Who else in the FFVII crew would be able to pull that off successfully?

2: She's the ONLY member of AVALANCHE that has been trained as a ninja, if that isn't groovy then I don't know what is!

3: She's the youngest member of the FFVII gang to have killed Sephiroth, I can't see Red XIII beating Sephiroth when he was 16.

4: She could easily whip Aeris' arse in a fight! (but then again, who couldn't?)

5: Her attitude, most of the other chatacters are rather angry, she keeps her cool and still has a laugh!

6: She has her own secret quest in Wutai, as far as I know no one else has that!

7: That groovy white glove thing, if her Boomerang doesn't come back she can clock someone with that!

8: At the end of FFVII she gets all the materia, that's sooooo groovy!