Capped Crusader Achievement in Little Kitty, Big City

There are a total of 42 hats required for this achievement. For some reason, the hat menu ingame shows a bunch more spots after the 42. I'm not sure what they're for, but they aren't needed for this achievement. Hats come from three general sources:
 

• Specific quest rewards (and one for beating the game)
• Bought from machines around the city with Shinies
• Located around the city as collectibles

The first type will come naturally while completing all quests. The second type are via the dispensing machines outside of shops. When you approach them, Crow will land on top and sell you hats for Shinies. The third type is best found after beating the game. After you beat the game, Crow will mark your map with all hats you haven't found yet. This makes mop up very easy.

Refer to the following video for any hats you may be missing, and how to get them.