In terms of gameplay, the ARMS fighter will be very fun and unique, being from a long distance arena fighter. I also think most of, if not, all of the characters are well designed. But, in terms of popularity, why is a character from a mediocre arena fighter getting a slot in a game about legends of gaming coming together for a brawl? The only reason I can think of is a sequel to ARMS. And despite it being kind of a joke, it would be awesome if Sakurai juked us and added Paper Mario, to promote both The Origami King and ARMS 2. Anyway those are my thoughts on the DLC for June.
Use Google, Youtube - whatever you've got at your disposal.