here are some ideas me and some of my friends thought of.
shiny bromons: each bromon will have a shiny skin once you catch the shiny one. you can choose if you want the shiny or regular.
trading/giving: if you need help getting bromon because you have bad ones. then ask someone to trade/give a better bromon so you can get the bromons.
evolution: after winning with the same bromon for a couple of times. then it will evolve making it stronger. lets say burger turtle. after 5 wins with him he becomes double patty burger turtle
that’s it thank you