In the Sinnoh region, there is a beach on Route 213. What I'm wondering is if this beach gets new hidden items everyday like those beaches in the Gen III games.
No it doesn't, and my source.
Although in this link it does include some hidden items that you will find, but only once.
How to change your username
How to add a user avatar
Why was my post hidden?
Flags vs Downvotes
Official PokemonDb League
Type a Pokemon name, type, move or ability to see instant results.