Is Unstable Hulk legal in Standard, Modern, and Commander?

Unstable Hulk is legal in: Legacy, Vintage, Commander.

What type of card is Unstable Hulk?

Unstable Hulk is a Creature — Goblin Mutant. Its oracle text reads: "Morph {3}{R}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.) When this creature is turned face up, it gets +6/+6 and gains trample until end of turn. You skip your next turn."