I'm not sure. Generally, a Totem Pokemon has a distinct aura, and tends to be larger than others of the same species... so we should know it when we see it.

Anyway, since you're so chummy with that thing, you think you can make it hold still for a picture? [She holds up her Poke Finder and nods at the Haunter. At least she's gotten used to it existing in her general vicinity... sort of.]