Will Brock going back to Pewter City as a Pokemon Gym Leader?

C) At the end of the Master Quest series, Brock went back to the Gym, but he came back just after the beginning of the Advanced series. The events that led him to coming back are shown in the Pokemon Chronicles series, which shows what happens with people who Ash had met before, but who wasn't traveling with Ash at the time. As quoted in the theme song: "Old friends, New adventures".

In short, Brock went back to the gym, his mum had changed the gym into a water gym, and his dad was too scared to speak up. Brock wouldn't stand for it, and so fought the new gym leader (which is his mum). Brock won. When he left, the gym was deemed a Water/Rock type gym.

b) no because brock is the coolest character on there. he's my home skillet biscuit

A.) True. That's common Pokemon wisdom, Ever since the first generation.. *sigh*