"Description: We are contacting you because Nintendo's Characters on the profile are being used in a way harmful to the brand and without Nintendo’s consent. The use of Nintendo’s trademark and Characters may confuse consumers into thinking the content is sponsored or endorsed by Nintendo. The profiles offensive content may further lead consumers to have a negative or weak opinion of Nintendo and the Mark and Characters.

The content has since been removed, in accordance with US law and Tumblr's own copyright policies. "

This exact issue has happened before:
nintendoeverything.com/nintend…

From now on I will be labeling my fan art as parody so no one can confuse it with official art since that seems to be the crux of why my art was removed, though that likely means nothing legally.

-Update-
Here is some reading material on copyright that is very informative. Fair use and parody do not protect your fan art. It needs to be upheld in a court of law and can only be used as a defense, there is no automatic protections for fan art. Just be aware~

www.redbubble.com/people/byron…

chrisoatley.com/fan-art/