Is Giant Oyster legal in Standard, Modern, and Commander?

Giant Oyster is legal in: Modern, Legacy, Vintage, Commander.

Giant Oyster

Q: What type of card is Giant Oyster?

Giant Oyster is a Creature — Oyster. Its oracle text reads: "You may choose not to untap Giant Oyster during your untap step.{T}: For as long as Giant Oyster remains tapped, target tapped creature doesn't untap during its controller's untap step, and at the beginning of each of your draw steps, put a -1/-1 counter on that creature. When Giant Oyster leaves the battlefield or becomes untapped, remove all -1/-1 counters from the creature."

Creature — Oyster

You may choose not to untap Giant Oyster during your untap step.<br>: For as long as Giant Oyster remains tapped, target tapped creature doesn't untap during its controller's untap step, and at the beginning of each of your draw steps, put a -1/-1 counter on that creature. When Giant Oyster leaves the battlefield or becomes untapped, remove all -1/-1 counters from the creature.