I remember jester/joker popped up in a convo with Law and Caeser.
As for Monet, we don't know much about her now. I remember Luffy wanted about 9-10 people each with a specialty... so if we see anything unique about her... then maybe it'll be a sign she'll be joining
I suppose having someone who can fly is a strange advantage, but I'd have preferred a logia type finally. The New World is just full of 'em. And yeah, I feel like he'll be the key to disarming some dangerous weapon that CC has made, like he'll turn a nuke into clothes and the crew will be saved.
I'm looking through OP wiki now and it's saying CC required permission from Joker to take down the straw hats. How horrible must he be if CC requires permission from him? eek!
You never know man! I think they might get her to join. I bet at one point Caeser will be all evil and abandon her and Luffy will pick her up. Also, interested in the Jester/Joker
But out of all the abilities i've seen.... his has got to be really pointless. I'm still not sure what it does, but I just know he can make clothes out of objects.... don't work out at ALL!