Oh good, you found Morgana!

We are the Phantom Thieves. We came all the way from Tokyo because we received this mysterious letter.

"Dear Phantom Thieves, last year, Sephiroth poisoned all the Smash fighters. As far as I know, I was the only one to survive. However, I suspected Joker could have a vital role to play in fixing this mess. So right before he got poisoned, I took Pichu's focus band and put it on Joker. With any luck, Joker will have survived the poison with 1 hp remaining. Hopefully you'll be able to take it from here and heal him. I really hope so, because we can really use his unique skills in the battle to come. We'll meet soon. -B."