So from what I can tell, that phone thing is obviously the new Digivice. Kihira and Nene are rivals of sorts; we don't know if they're good or bad yet, but the other Digimon (primarily Shoutmon, Dorurumon, Starmon, and Ballistamon) can merge a la Jogress to form Shoutmon Cross Four. Kihira and Nene's might not be a part of it, or maybe their Digimon can merge as well. I'm guessing that there's a fourth kid as of yet unrevealed too, based on the four that merge and only three kids. Starmon is probably Akari's. That leaves either Dorurumon or Ballistamon for Zenjirou.
This is all speculation, mind you.