I just got access to the clothing store in lumios city but everything is so expensive. the shirts are 100,000 and I only have 400,000. how can you earn money I know you can vs the league but are there any other good ways to get money?
Yes, at Restaurant Le Wow in Lumiose City.
Bring a couple of pokemon and an amulet coin for more money. Tell the waiter that you want to try the Double Meal Battle, and you will fight 5 trainers, where your pokemon are healed after each trainer.
You can also use an O-Power here to get even more money.
A more descriptive guide can be found here.