Yeah, gonna have to correct you there.
It's the third slowest grass starter ever. Torterra and Chesnaught are slower, everything else is quicker.
EDIT: I'm agreeing with @Julius though. That screenshot showing an Oshawott at Level 50-ish early on was very suspicious. They're hiding something with the final evolutions. I'm sure of it.
I don't agree that the regional variants have been as mixed, almost all of them have been hits for me. Whether it be cool takes on old designs ("KISS fan" Zigzagoon) mechanical tweaks that save a Pokémon from mediocrity ("It's better when it's dead" Corsola), or a mixture of both ("Best regional variant" Marowak) I can't think of a single one that I don't think is better then the original version.
But hey, if the starters have regional variants, maybe Decidueye won't be so slow!