A transform boundary is when one plate?

Convergent plates are two tectonic plates that are colliding as they move toward each other. There are several types of converging plate boundaries.

Oceanic to oceanic plate convergence:

Where an oceanic plate collides with another oceanic plate, the more dense plate sub ducts into the mantle. The subduction results in the partial melting of lithospheric rocks above the area of the subduction, causing underwater volcanoes to form. If the volcanoes grow to reach the surface, volcanic arc islands are formed.

Oceanic to continental plate convergence:

Where an oceanic plate collides with a continental plate, the oceanic plate is subducted due to the fact that it is more dense, which can also cause volcanism and mountain building.

Continental to continental plate convergence:

Where two continental plates collide, neither subducts into the mantle, the crust is thickened, and mountain ranges are formed from the thickening and uplift.