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.
EverGrande City
FAP
No
play around
Wallace is the champion of the elite four in Pokemon emerald
how to beat Pokemon emerald
the elite four is in ever grande city you will need waterfall to get there and surf.
You find him in meteor cave after beating the elite four.
in the Pokemon league in evegrand city
when you beat the elite four
Beat Elite Four.
Possibly