So I found out yesterday that I have been being lied to this whole time about Animagi and Metamorphmagi.

Apparently you don't need a spell to turn into your chosen animal if you're an Animagus. But you do if your Transfiguring. The latter makes sense.

So that makes Xavier an Animagus I guess? Cool

My source is the Harry Potter Wiki, specifically this quote:

"The difference between Transfiguration and the Animagus transformation ability is that an Animagus can change into an animal whenever they want, without a wand or an incantation. Being an Animagus is an ability, and Transfiguring requires a spell."