A common theme shown the game so far are these star-like shapes. What does it mean? The battlefield surrounded by all the types being a focus of the trailer combined with the gimmick symbol surely means something important.

I think the battle gimmick in this game will involve trainers influencing battles through field effects or other external means, rather than buffing the Pokemon. My crackpot theory is that there are now trainer classes/themes that correspond to a certain type, and each one has unique pros/cons. This would be an interesting way to shake up the gym theme formula, and the class concept is common in competitive games these days making it a fitting next step for PvP.