Is Shapesharer legal in Standard, Modern, and Commander?

Shapesharer is legal in: Modern, Legacy, Vintage, Commander.

What type of card is Shapesharer?

Shapesharer is a Creature — Shapeshifter. Its oracle text reads: "Changeling (This card is every creature type.) {2}{U}: Target Shapeshifter becomes a copy of target creature until your next turn. *One good mimic deserves another.* Power/Toughness: 1/1"