After the November Super Mario Maker update, players were able to access special Event Courses in Course World. These were official, original levels distributed by Nintendo for limited amounts of time online. The highlight being that some courses also provide new costumes for the Mystery Mushroom. Two new courses are now online that provide Cat Mario and Cat Peach courses.
Cat Mario and Cat Peach are stars of The Cat Mario Show, a series that has been running since February 2014 to educate people about various Nintendo games. They each wear the cat costume from Super Mario 3D World. Playing their respective courses unlocks their outfits in slots 105 and 106 in Super Mario Maker.
Cat Mario’s course is the easier of the two and provides many opportunities to earn 1-Up Mushrooms. Cat Peach’s course is far more fiendish. As a word of advice, jump right under the coin to the left of Mario’s starting position, jump on that block, jump to the question block, then jump upward. If you can reach that point, you can beat this level.
The Cat Mario and Cat Peach levels are immediately available in Super Mario Maker for the Nintendo Wii U.