Almost the same treatment as the MP4 announcement.
For a moment, I thought both Isabelle and Tom Nook were getting in. Isabelle looked to be more of an original fighter with her moves so then I thought maybe Tom Nook (who's been in the series longer) was getting the nod as an echo fighter of Isabelle. Considering how Smash seems to be making an effort to have more series villains in it and Tom Nook has sort of been seen as the de facto villain of Animal Crossing, it seemed to be all coming together in my mind but then suddenly it was a reveal for AC Switch.