There are a few projects like this, most notably Pokemon Lard which is an entirely custom game with redesigned pokemon and custom pokemon. I haven’t played it since the first demo released, but iirc there’s player weight gain and NPC weight gain involved.
There’s also a short parody game that involves pokemon characters, Pokemom wide. It’s around 10-15 mins long.
Then there’s this romhack of Fire Red that replaces most of the mons with fatty sprites.
Also as Arro said, there should be a globe icon at the bottom of this message to translate it to your native language.