where to train pokemon after completing the game?

im playing on soul silver and it doesnt have the vs seeker, so where can i train pokemon untill there like level 60ish that doesnt take much time? i have a lucky egg.
I just dont like the idea of going through the elite 4 40 times a day lol

You can use trainer rematches. There's a list on serebii of all the trainers you can call for a rematch on specific days. You can also rematch against Gym Leaders at certain times. Battling the Elite Four is probably easier and faster though