They often gather near places frequented by electric Pokémon in order to avoid being attacked by bird Pokémon.
– Pokémon Moon Pokédex
Grubbin is the early bug Pokemon of Gen 7. Its Pokedex entries and appearances in the anime say that it lives underground and is a good digger, yet it’s not Ground type. Its Moon Pokedex makes it seem pretty smart, hanging out near Electric Pokemon to avoid bird Pokemon.
Its stats are pretty unremarkable, being pretty evenly distributed.