Just a warning for anyone who owns any Mario Sports Superstars amiibo cards. There is a low chance that an amiibo card may not work at all for whatever reason. My Horse Racing Rosalina I got in a pack last night isn't working at all on my 3DS. I don't have a double of Horse Racing Rosalina either so I'll have to hope I get another one in a pack soon or buy one separately online. Apparently Nintendo (of America at least) won't do anything to help.
This seems to be a thing only with Horse Racing cards from what I've heard. The Horse Racing cards may also actually come damaged. I've noticed this on five of my six Horse Racing cards; Yoshi, Waluigi, DK, Baby Mario, and Birdo. They all work fine. Rosalina does not have any damage but this card is the only one to not work at all. It wouldn't scan no matter what.