>>27376267Aside from the starter evos I mentioned...
Komala evolves into Narcolyptus, a giant, half-awake Normal/Ground type koala resembling some ice age monster.
Bewear evolves from Bearfraid, which has a better design because it actually looks like a red panda.
Drampa evolves from Dradult. There's no Dramma mon, but there is a Poison/Fairy fey queen counterpart called Eldering. It's found at night while Drampa is found at day, and they can produce one another's offspring through breeding.
Then there's Painsporum, a Normal/Grass bread loaf fungus mon. It's entries talk about how toxic it is, and it learns a fair amount of poison moves so I think it'll evolve into a Normal/Poison type.
Now, for Megas...
Machamp, Slowking, Donphan, Flygon, Milotic, Honchkrow, Spiritomb, Probopass, Froslass, Heatran, Galvantula, Chandelure, Beheeyem, Volcarona, Genesect, Pangoro, and Malamar all get Megas.
>>27376365More than Kalos and Johto, but less than Hoenn. There are more regional dexes than Kalos, one for each island, so even though there are much more mons, you probably won't encounter them super frequently.