Is District Mascot legal in Standard, Modern, and Commander?

District Mascot is legal in: Standard, Modern, Pioneer, Legacy, Vintage, Commander, Historic.

What type of card is District Mascot?

District Mascot is a Creature — Dog Mount. Its oracle text reads: "This creature enters with a +1/+1 counter on it. {1}{G}, Remove two +1/+1 counters from this creature: Destroy target artifact. Whenever this creature attacks while saddled, put a +1/+1 counter on it. Saddle 1"