Just recently we reported on Nintendo opening legal proceedings against a Tokyo-based karting company that uses the name 'Maricar', citing copyright infringement. The company allows licenced drivers to take customised karts out onto real roads, with services including the rental of Nintendo character costumes. Nintendo was so hot under the collar about it that it issued a statement just to announce the fact its claim against the company was underway.
While that legal case is ongoing, it's emerged that Nintendo had a previous effort to target the karting business thrown out. Public visibility has now been given of a decision made in late January by the Patent Office, in which it rejected Nintendo's objection to the Maricar trademark. The decision ruled that 'Maricar' isn't a commonly used abbreviation of Mario Kart, and that it's "an unassociated trademark".
Nintendo's legal case, ultimately, has widened the scope in targeting the company's use of Nintendo IP (through costumes etc) without permission and in promotional activities.
Whether on YouTube or in targeting quirky karting companies, Nintendo still remains active in trying to protect its IP, even if its methods or reasoning prove to be extremely divisive.