Pokémon Sun and Moon - Incineroar is not a fight type pokemon

Incineroar looks like Tiger the Dark

Also Incineroar is a Heel Wrestler, someone who plays the bad guy in the ring and uses dirty tricks to win fights and get the Audience Rilled up. Remember dark type is called evil type in Japan so dark type doesn't always mean darkness, it can mean unfair/nasty fighting. So a Villainous Pokemon that fights using cheap tricks would fit a under evil type, Thus be a dark type.