Well, Chopper kind of did, but that doesn't really count since he could've always done that. Did Nami get a power up? Don't recall. I remember her winning through a combo of her wits and Kalifa(sp?) being a ditz/more interested in testing her new powers.
When I was first reading through the arc I was ready to call bull as I read through the fights. Not so much now, but they still nag at me sometimes, as it just feels a little convenient/like other battle shounens. It's the only time this has happened in the series, at least to this degree, but still. Luffy's Gears are probably the best explained, although I'm not a fan of the whole "I came up with it by watching you do your thing" thing, plus the pseudo-science involved is 'eh' at best. I don't really remember how Sanji got his. Zoro's is the weirdest, as it seemingly came out of nowhere, but we've barely seen it since so I suspect even Zoro doesn't know anything about it. I've heard a number of theories about his ever since.