I'm too lazy to count myself, but I can give you a few tips.
Look at a list of Pokémon appearing in the Hoenn Dex, such as this one.
Subtract Surskit, Masquerain, Meditite, Medicham, Roselia, Zangoose, Lunatone as well as the usual suspects - trade and event Pokémon.
Add the non-Hoenn Dex...