Pokémon - Arcanine was originally a Legendary Pokémon.

He may be the Legendary Pokemon but he still has to beg if he wants a treat and belly rubs.

This is actually 100% true.
Arcanine was originally going to be a Legendary Pokémon in the games, but was eventually replaced by Moltres when Game Freak decided to make all three of the first Legendary Trio birds.
Since they didn't want to scrap a perfectly good Pokémon idea, they decided to make him the version counterpart of Ninetales, and gave him a Pre-Evolution in the form of Growlithe.