Allright. I know my fair share of greece mythology so Ill try bounce some ideas around. (I dont draw much so Ill leave it to others.)
Few greece mythological beings that could be considered:
A Manticore. Poison type pokemon perhaps?
Hippokamp (not sure I spelled correctly.) A half horse half seahorse. Usualy poseidons mount. Water type?
Medusa. poison/dark or something.
Cerberus. Dark/fire. Hades's guard dog.
Cyclops. Normal type fatty.
Harpie/Harpuia/Harpy A flying/dark type perhaps.
Pegasus. Flying type of course. Connected to zeus of course.
Minotaur. Fighting type?
Hydra. Grass or poison?
Siren. A water deity.
Scylla and Charybdis Twin water demons. Maybe water and other type for each?
These are few I came up with. I hope they serve as some inspiration for you or others. Ill continue to post some ideas.