Happy Pokémon Day! Yep, I had no idea this was a thing, either. Nevertheless, it turns out that 27th February marks 24 years since the launch of Pokémon Red and Green in Japan so a handful of events and offers are running a to celebrate.
Starting off at the Nintendo Official UK Store, you can enter the voucher code 'TEAMBLUE' to receive a water partner Pokémon mug or 'TEAMRED' to get a fire partner Pokémon mug for free with any Pokémon games and Pokémon console bundle. This includes both pre-orders for Pokémon Mystery Dungeon: Rescue Team DX or the Pokémon Sword and Shield Expansion Pass.
You can find everything that's eligible for the offer on their Pokémon Day 2020 store page. No massive reductions here, then. Just a neat little freebie to go with your purchase if you were considering picking up either anyway.