@Urouge:
Maybe we don't have a solid definition of flying that we agree on. I view the power of flight to be full control in the air. Up, down, left, right, stop, go, etc. Buggy can do this with 90% of his body.
Then your definition should include 100% of their body 100% of the time. The ability to fly suggests (in this case) unlimited control in the air.
The problem is that we have people like Robin, Kizaru, and various other logia's that can theoretically fly as well, with each of them having a constraint of sorts. I wouldn't say any logia's can "fly", but that they can travel from one location to the next via their Devil's Fruit. Essentially they break their body down into their element, stretch their body via their element to their destination, and then reconstruct their body at the other end. This is not flying, so to speak, but rather connecting their body to two different locations and then traveling to the other end through the air. The primary difference being that it is (presumably) short range, consists of two specific points, and does not allow free control in the air (read: defying gravity). I would see it as something akin to jumping, being essentiallyno different than Luffy doing his Gomu Gomu no Rocket to launch himself through the air from one location to the next. Then you have Robin who, while having the ability to make functional wings, lacks the physical strength to maintain the form that allows her flight. Theoretically she could fly if she trained and became as strong as someone like, say, Zoro. Due to this, I would THINK Pell was referring to Zoan's specifically. That, or these are "rule-breaking" abilities, that don't quite fall into the category that Pell was referring to. Then again, was Pell's line definite? I mean, did he say something absolute or did he use a word like "recorded", meaning a specific amount currently known. Not that it would change much.