Its preferred food is dravite. After it has eaten this mineral, crystals form inside the Pokémon, rising to the surface of part of its body.
– Pokémon Sun Pokédex
Alolan Graveler is Rock/Electric type instead of Rock/Ground. Its Pokedex entry describes its favourite food as dravite, which is a dark brown crystaline mineral that looks pretty much the same as Alolan Graveler’s eyebrows and sideburns.
The Rock/Electric type combination is unique to the Graveler family. It’s not a very good defensive type, being 4x weak to Ground. But hey, at least it’s not 4x weak to both Water and Grass anymore!
Its hidden ability Galvanize, is unique to its family. It causes all Normal type moves to become Electric type and receive a 20% power boost. It could be good, since it means Graveler can get STAB and extra power from moves like Explosion and Double Edge (especially since the only physical Electric move it can learn is Thunder Punch, so Galvanize can give it other physical Electric move options). On the other hand, it means Ground type Pokemon are immune to Graveler’s Normal moves too.
Stat-wise, it has the same stats as Kanto Graveler, with high Defense, good Attack, but low Speed and Sp Def.