Clash and "all champions unlocked

"All champions are unlocked in Clash, so don't worry about figuring out that complicated three-person trade from solo queue."

That's the word for word quote from the FAQ on clash. Does that mean I could potentially play a champion in clash I don't even own because I locked them in and didn't trade. The reason this worries me is because it could lead to awkward moments where my teammate wasn't pay attention, which is their fault but at the same time. Is it possible to play a champion you don't own in clash?