As those are the same character models of the protagonists (just customized), it's a pretty safe bet to assume that the names will be those as well. It could very well end up being Xavier/Yvonne, but until we know for sure I'm gonna leave it as is. I'll update it accordingly if they do confirm that though!
Serena or Calem will be the name of one of your rivals (and I'm guessing it'll be your main rival).
According to the screenshots, Xavier and Yvonne will be the names of the protagonists, even though it hasn't been officially confirmed yet.