Is Clockwork Dragon legal in Standard, Modern, and Commander?

Clockwork Dragon is legal in: Modern, Legacy, Vintage, Commander.

Clockwork Dragon

Q: What type of card is Clockwork Dragon?

Clockwork Dragon is an Artifact Creature — Dragon. Its oracle text reads: "Flying This creature enters with six +1/+1 counters on it. Whenever this creature attacks or blocks, remove a +1/+1 counter from it at end of combat. {3}: Put a +1/+1 counter on this creature. Power/Toughness: 0/0"