Gigalith, labeled The Stupid Thug, is one of the guests that are trapped in the Unova Mansion.
In Boom!, Gigalith is the 18/19th person to arrive at the Unova Mansion, along with Emboar, complaining about all of the other people in the mansion as well. Later, he and Emboar challenge Krookodile and Scrafty in a game of pool. He claims that all of the other pokemon there are a bunch of babies and there is nothing wrong with the Unova Mansion. When Haxorus finished reading a note aloud, Scolipede called him an idiot after he's wondering that who say it's a host. He is about to finish a game of pool with Emboar until Krookodile's sinks the eight ball in one of the corner pockets.
Still believing that the note was a stupid prank, he went upstairs so he could get to his room before he suddenly stops in front of the door in confusion, wondering whether or not the door is actually his. Gigalith twists the doorknob in order to gain access inside, only to be met by an explosion. The impact of it causes the pokemon to fly backward, tumble down a flight of stairs, and hit the carpet of the living room, ultimately causing his death.
- He's the first main characters in the Unova Mansion to died.
- He's also the first male to died.
- Gigalith, along with Stoutland and Scolipede is the only characters in the Unova Mansion to have four legs.