So I've been thinking about a new Mario Strikers game for the NX (I think the ship has sailed on the Wii U) and I'm trying to think of potential newcomers to a hypothetical NX sequel. Charged received Bowser, Petey Piranha, Diddy Kong, and Bowser Jr. as new captains and several newcomer sidekicks.
When thinking of characters for this game, the Captain roster is quite smaller because many other iconic Mario characters become Sidekicks. Basically with the exception of Yoshi, any character that is a member of a species is usually relegated to a sidekick like Hammer Bros, Koopas, and Toads. So I'm actually struggling to think of characters to add at this point.
For Captains, the immediate first ones that come to mind are Dixie Kong, King K. Rool and Rosalina. King Boo is a good choice too, though he'd essentially just a bigger version of the sidekick Boo with a megastrike. But I can hardly think of new sidekicks...Lumas for one, because of a captain Rosalina. We already have Kritters as goalies so I can't think of a new Kremling sidekick.