You’re bitten by a Pokemon & transform into a Pokemon same species as the one who bit you at the full moon. Your Pokemon form has a completely different mind & acts based on instinct rather than thinking. Also, you can only say your species name & variations of it in your Pokemon form.
You don’t actually start transforming until you get home, and whoever you live w/ may walk in on u.
When the full moon’s gone, though, you turn back into your human form w/ no memory of your actions as a Pokemon.