The Blast Pokémon!
Their shells are packed with metal which bursts if disturbed causing damage to their surroundings. As such, they hide away as this leaves them vulnerable until they are able to regrow their shell.
The Big Blast Pokémon!
Being upside down means that all its life-force has gathered into its head and shell. The built up pressure is released in a great explosion when this Pokemon feels threatened.
by vital-ET