I think that you definitely missed some things here.. Why didn't you just say that you were drawing a Pikachu and sai that you only wanted to show it off to your friends..?
My mom wouldn't let me play it because when I was younger I'd believe anything XD now that I'm older she lets me play it as I know better than to say that pokemon are real which they arnt XD
Oh man hahah, i'm surprised the teacher didn't know what a pokemon was. Considering he/she is a teacher, and you know... works with kids. If that was me, I would continue to sneak around and play as well hahhaha.