Thanks for playing!
The balance of the fights themselves is hugely reliant on the teams other players made, since its an async multiplayer game.
Each level of trophy gets taken into account when rolling an enemy team to fight. to prevent fighting teams that are too under/over-leveled for you.
Can't provide much exttra dev insight in the other parts you mentioned as I purely was onboarded as the backend dev :D
Maybe NaturalPower can though!