Hi Chris. Actually it's like this. The top,pants,dress,socks,shoes,These are the things called daily necessary clothes. You need to use "chuan" for necessary clothes. But other things like gloves,ties,scarf,belt,earings,hairpin,glasses,ring, These are the accessories, That means it's daily necessary clothes. You are totally okay going out without it. So for accessories you need to use "dai" or "ji", Oh BTW we got one more word for wear that is "ji", Are you aware of the difference between "dai" and "ji"? And for your question sports mascot costume, We'll use "chuan". Hope this will help you!