Pokémon have always had various ways of evolving into new beasties, and the ones featured in Pokémon Sword and Shield is no different. One of these curious contenders is the unassuming Applin, which can be found primarily on Route 5, just east of Turffield. You won't see any wandering around, though; instead, you'll have to look out for exclamation marks appearing in grassy patches in order to find one.
This little critter actually has two possible evolutions, and which one you’ll get all depends on which version of the game you have. Regardless of which version you own though, the process of getting Applin to evolve is essentially the same.
Once you reach the town of Hammerlocke, you’ll need to travel west past the Pokémon Centre until you reach the point you see in the image above. You’ll find a young chap here who wants to impress a lady friend and asks if you have an Applin for him to use. Don’t worry, you won’t lose your Applin by agreeing, instead things won’t go entirely according to plan for him and he’ll return your Pokémon to you. More importantly, he’ll also give you a special kind of apple.
If you’re playing Sword, he’ll give you a Tart Apple, and using this item on your Applin from the ‘Other’ menu in your items bag will cause it to evolve into a Flapple.
If you’re playing Shield, you’ll instead be given a Sweet Apple, and by using the same process as you would in Sword, your Applin will instead evolve into an Appletun.
If you've already done this and still want another one, you can find the respective Apple for your version in the Wild Area. They're rare, but they're definitely out there!