Super Mario Odyssey just updated to version 1.2.0. With updates come patches, and with patches come dataminers. And thanks to these dataminers, we now learned some information about new costumes Mario will be able to obtain in his journey around the world.
Eleven hats and ten suits were leaked thanks to the datamine. Among these are costumes based on each of the Broodals, an 8-Bit Mario hat, and a zombie getup complete with an axe to the head. You can see a number of these in the gallery below! Another set called the “Link Hat” and the “Link Outfit” was present in a previous datamine, but that one was mysteriously removed in this update, making the current status of the set unknown.
While the way to unlock these costumes is still unknown, previous post-launch costumes were available for purchase at any Crazy Cap location. This likely means that the next crop of costumes will be available to all players the second Nintendo officially releases them.
Source: Nintendo Everything