I would think there should at least be a controls tutorial/guide, especially where the official control scheme of a game (i.e. Rockers having a hold-and-flick touch screen system in DS) is entirely different from how it works in Studio. Even just a controls-list readme like "in DJ School, hold A to stop the record, then [insert action here] to Scratch-O" would go a long way to help.
Requiring prior knowledge of the official games to know how to play a game well is fine. Requiring trial-and-error to figure out which inputs do what game actions is a bit much.