Currency is a form of player reward within the game, much like crates.
There are currently two different forms of currency within Smash Supreme; Gold (Soft Currency) and Gems (Hard Currency).
Currency can be used to upgrade moves, purchase a different form of currency, purchase items from the shop such as moves and crates or alternatively, put away for a rainy day!
Certain aspects within Smash Supreme will require a certain form of currency and not allow the other, this is something to be taken into consideration before any payments are made.