This is for people who have an ar. First enter the walk throgh walls code which is
CF010EDC
CB42FC3A
78DA95DF
44018CB4
Then enter a code for any Pokemon you want like Jirachi.
Then fly to the tower and walk past the lady into the rooms. You will now battle people with the first three Pokemon in your part.
WARNING: you will battle people at lv. 50, or at least I did.
PS. could someone tell me how to enter the locked door in the oldman's house in Mossdeep city?