Who's That Pokémon? (8)

It is a dog (Google says tiger, but I really don't think it's a cat!) able to run at 6200 miles in a night and day. It is incredibly loyal to its trainer and in some games you cam ride on its back. In older Pokedex entries it is called "legendary" and "majestic" but it's a pretty common Pokemon.

Who's that Pokémon?