Note: even though this flash game was downloadable from the official Mario Power Tennis website and has the the game's logo in the bottom right corner, the flash game itself has nothing to do with the actual game, or even tennis in general. In fact, it features Paper Mario trying to win at that carnival game where you smack down a hammer with as much strength as you can.
They had to know what they were doing by putting Wario, a character that got a second starring role in a series for being known for doing stupid things in a safety video
I'd imagine with this info, the one who teaches the ones who serve in Nintendo's cafeteria is Dedede