To get items..
Talk to moogle to start.
/cheer Mumor On! ( must target her)
Mumor will ready 4 of the dancer dances.
Target Ullegore and get ready to dance at him when she says shes "going to use her ultimate attack" Each one will have the according name:
Super Crusher Jig ( jig)
Shining summer samba (samba)
Lovely Miracle Waltz (waltz)
Neo Crystal Jig (hi2u sailor moon)
target mumor again and continue to cheer her on, rinse and repeat.
You only have a 3 second window to get the dances off so macro them while keeping Ullegore targeted. When in doubt just look for the animations to match up the dances. It is very helpful to turn off /emote text and /names so you can see. I found angling my camera angle from a birds eye view at my character helped a lot too.
either use your mouse to target the NPCs or stand in the middle of them and turn and face the proper one at the proper time. ( no you can't <t> them. it has to be f8 or with a mouse, or scrolling through ( which does not work well with so many people there)
You have to get at least 15 messages that says your dancing synchronized with Mumor to get a piece of swim wear they do not have to be one after the other, so don't freak if you miss one. just keep going till you have 15+ I did 20 just to be safe. You should do this even 3 times in a row BEFORE talking to the moogle again. if you go back after one session, all you will get is fireworks. (figured this out after..about 4 stacks of fireworks. lol)
to get the HQ: 15ish matches on hard mode. (maybe you can't miss in a row and have to go to the other nations) I have not bothered with this yet, but it seems you have to get all 3 key items ( red balloon / sandy blue balloon / bastok, green balloon / windy ) and trade them to the moogle to get your HQ set. It looks like they give you both items at once, but don't quote me on that.
hope this helps @_@ yay summerfest!
on that note..
F yeah sailor moon!