Forum Thread
Low on Cash!
Forum-Index → Help → Answered → Low on Cash!My trusty partner!
Other than that, I would say to sell/auction extra pokemon, sell unwanted items, and save up for the rumbling bag.
Also, use the GGC you get from interacting on the golden slot as well, since you can get items from there to sell to other players and the shop.
I also recommend keeping up with rumbling! You'll get some pretty great things from there to sell such as mystery items, star pieces, gems, etc. And of course it gives you PD too.
Also here is a very useful thread with item prices/value, useful so you don't get lowballed/scammed when selling.