Slugfugg has the highest base Defense stat of all Poison-type Pokémon.
Slugfugg, along with Fireshitre has the highest base stat total of all non-legendary Poison-type Pokémon.
Slugfugg is female only
On April Fools' Day 2019, Slugfugg was given a fake alternate form called "Slugfemm," playing up on the over-sexualization of Goodra.
Before the official release of Clover, the shiny form had its colors reversed.
Slugfugg is the only Pokémon to have its shiny appearance change within its evolutionary line.
Slugfugg is based on the /vp/ meme of 'Goodra is female only', in that it starts as a 100% female species and becomes a 100% male one upon evolving. The fact that it changes gender upon evolving may also be a reference to the fact that actual snails can change their gender at will. Its shiny form is in reference to Goodra itself.
Slug, and 'fug', previously explained on Heliofug's Page. It likely also derives from "Slugfucker", one of the nicknames of FemaleGoodra, the poster responsible for the "Goodra is female only" shitposts.