What do you do in Pokemon Emerald after the Elite four?

Answer 1

you go to a place called the battle frontier where you try beat the battle aces. you also have to fight SSteven who might i warn is very strong. his Pokemon are 20 levels above Wallace. you also have to finish your pokedex.

Answer 2

you can train all your Pokemon and also get friends to watch you beat the elite four and dazzle them

Answer 3

you get to go to battle frontier or battle elite four again