Larvitar is found in Game Boy Advance's Pokemon LeafGreen game in the Sevault Canyon sub-zone. Sevault Canyon is a sub-zone located in the middle of Island Seven in the Sevii Islands. Island Seven is accessed by obtaining a Rainbow Pass on Island One, which itself is accessed from the ferry in Vermilion City.
Larvitar, the Rock Skin Pokemon, is most commonly found in the wild, in a patch of grass in the middle of Sevault Canyon. He can be caught at any time of day with an appearance rate of 5 percent and a catch rate of 6 percent. Larvitar found in Sevault Canyon will be between level 15 and 20.
If a player does not have access to the Sevii Islands, he needs to talk to Bill in Cinnabar Islands, defeat the Elite Four and receive both a Tri-Pass and a National Pokédex. After achieving these milestones, he may access the Sevii Islands via the Seagallop Ferries at Vermilion City. He will need to venture to Island One beforehand and acquire a Rainbow Pass from Celio before he is permitted into Island Seven. Sevault Canyon is right behind the Island Seven city, and Larvitar is found in the grass patches there.