Within the local play area called the shoal in Splatoon 2, you can play with local players.
I have seen a stamp card where you can collect stamps on but
How to collect them and what will happen if you complete a stamp card?
I can't find this anywhere and I don't know why it is there at all.
Best Answer
If you complete a stamp card, you will get a Crust Bucket ticket.
Source(but the source is written in Japanese)