Isn't this an IP/copyright violation?
I know a couple of years ago nintendo did a sweep of the app store and nailed everyone using their licenses inappropriately.
I had a couple of those soundboard apps and they disappeared from the store, and I couldn't find them again for a new iPod touch later on
Just be aware that nintendo has people scouring the app store and they do not like anyone using their characters, likenesses, artwork, sound, music, etc for any unlicensed or specifically legally-allowed purposes.