Is Champion of the Clachan legal in Standard, Modern, and Commander?

Champion of the Clachan is legal in: Standard, Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Champion of the Clachan

Q: What type of card is Champion of the Clachan?

Champion of the Clachan is a Creature — Kithkin Knight. Its oracle text reads: "Flash As an additional cost to cast this spell, behold a Kithkin and exile it. (Exile a Kithkin you control or a Kithkin card from your hand.) Other Kithkin you control get +1/+1. When this creature leaves the battlefield, return the exiled card to its owner's hand."