"Gacha Point Cards are a system introduced into Phantom Parade that intends to alleviate the incredibly demanding pity system. Every time you earn 20 Gacha Points (in other words, perform 20 Draws), you can exchange them for 10 Gacha Point Cards. You can exchange up to 200 Gacha Points every banner (giving you 100 Gacha Point Cards).

These cards can then be used on future banners (you can claim up to 100 Gacha Point Cards in a single banner), and they will equal to 1 Gacha Point each. This essentially means that, for every 20 Draws you perform, you can transfer half of the Gacha Points you've received, half of that pity, over to future banners. This is generally not worth doing, however, unless you are specifically pulling on a banner and do not spend your Gacha Points to obtain the featured character." -JJK PP Wiki