A lot of the pokedex entries of pokemon are pretty dark. There's Honedge, with is a disembodied spirit living inside of a sword. There's Drifiblim, that drags children down to the underworld. There's Shedninja, which steals souls of those who look at its back. There's Grimer, where in whatever place it moved in there plants can never grow ever again (as it is living toxic sludge).
Shapeshifting, time-travel, psychic powers and producing water from nothing would be possible.
Your childhood dream of teleporting somewhere with Abra because you're late would be possible.
Farfetch'd would have their leeks confiscated and replaced with swords.
Delibird would be considered a terrorist.
Harmless Pokemon battles would turn into public disturbances and later break out into city-wide riots because nobody likes to lose.
A Pokemon's habit of having the "I FOLLOW MY TRAINER BLINDLY" mindset, means they'd be fucking retarded.
There'd be groups dedicated to the protection of Gardevoir.
Dragons would actually exist.
Meowth and Persian would be captured and forced to produce coins through the use of Pay Day. Their widespread capture would render them extinct in the wild, and Pay Day would cause inflation in the economy.
HP UP, Protein, Iron, Calcium, Carbos, PP UP, PP MAX and Rare Candy would be considered steroids.
Misty, Cynthia, May, Dawn and other female characters from the anime would get raped constantly.