Like everyone else, I agree on Chaizard being dragon-like.
If a winged, fire-breathing lizard isn't a dragon, what is? Except for the fire on the tail and shape of its torso, I was surprised when I heard it was actually Fire/Flying.
Gyrados, too, seems like a dragon, being sea-serpent, which I believe is a member of the draconic family. I mean, in what way is it a flying type? It can't fly!
I totally disagree with Lugia being Flying/Psychic. As much as I like Psychic types, it seems like a dragon-like creature that lives in the water, which is why I think it should be Water/Dragon. I know it's a weird type combination, but it does make sense, especially after we learn in Pokémon 2000 that it likes in the sea.
Rayquaza seems a bit draconic as well. It's also more serpentine, but it could pass as a dragon, especially with the shape of its head.
~Psychic