I assure you. Surviving against the Brotad will give you rewards far beyond your imagination [that you may or may not comprehend!], thus bragging rights and the title of HE WHO SURVIVED THE BROTAD! :D
Do I get to meet the Vanillite I have been chasing since last december and wasted 3 pokéballs and a pokémon on?
Awaiting your GM quote,
I couldn't have phrased it better. You are free to do as you like when it comes to wild encounters... we just deal with whatever you catch them or not... and sometimes throw random wild Pokemon at'cha