A few of my thoughts on typings....
What the hell is up with the Normal-type? On one hand it seems to be for those Pokemon who are just that, normal, with no elemental powers or anything (ie. Rattata, Pidgey, Tauros and the like). However, there is also a lot of evidence saying that Normal is a catch-all "other" type, for Pokemon that are completely the opposite of normal, and therefore don't fit anywhere else (Porygon, Ditto). So which one is it? If it's "normal", then there are a load of Pokemon that just don't fit. If it's "other", then what, may I ask, is the point in having "other" as a sub-type?
On a seperate note, there are several Pokemon that I think should have had different typings.
Lugia - Psychic/Flying, should have been Water/Flying. More appropriate for the "beast of the sea", and a better opposite for the Fire/Flying Ho-oh.
Psyduck/Golduck - Water, should have been Water/Psychic. It's Psyduck, for crying out loud!
Yanmega - Bug/Flying, should have been Bug/Dragon. Being a Dragonfly, Yanmega was the perfect chance to try out a new and interesting typing, but obviously the creators were scared of change and decided to go with the boring, repetitive, and not very useful Bug/Flying typing.
Lumineon - Water, should have been Water/Bug. Again, a great typing that would have made Lumineon both useful and interesting, as it is she's forgettable. She's based off a sea butterfly, so it makes perfect sense.