Yeah, I wanted to see other people's opinions before posting my own. Personally, I thought Aerodactyl and Tyranitar could be considered dragons. Hmm, let's see...
Other Pokemon
Kecleon - Reptile, yes, but dragon, no
Squirtle - nah, a reptile but not a dragon
Bulbasaur - same issue
Torkoal - nuh-uh
Ampharos - Yeah, totally (from sheep to dragon? I've seen weirder things)
Larvitar - yeah, a baby dragon
Lugia - good possibility
Ho-oh - If Altaria can be a dragon and a bird, maybe Ho-oh could be one as well