The happiness of a Pokémon is something that you can influence as a trainer in Pokémon Sword and Shield. You also have different choices as to how to improve it.
Here are the different ways to elevate a Pokémon's happiness:
- Keep them in your party
- Have them battle
- Ask them to keep the Soothe Bell item
- Giving them curry at the camp
- Nourish vitamins
- Give them berries that will "elevate usability". Be sure to check a berry's description before giving it to them
- Catch them with a friend or a luxury Poké balloon
The quickest method is to keep the Pokemon with you in your party as you travel, fight against them, and give them curry, berries, or vitamins whenever you have the chance. Curry only arrives at your campsite, but you can give a Pokémon a berry or a vitamin whenever you have it in your bag.
There is also a chance to lower the happiness of a Pokémon. Here is how you do that:
- Keep them on your PC
- Use bitter objects on it
- Lose the Pokémon in battle
A Pokémon loses the happiness you have accumulated with it when you trade it and reverts to its base Happiness setting.
Unfortunately, you can't always see and stay alert for a Pokémon's happiness by looking at its stats. You have to look for the Friendship Checker, who is a little kid in Hammerlocke. You can find it in the building to the right of the Pokémon Center, at the entrance to Hammerlocke. Go inside and he'll ask you, "Would you like me to check if your Pokémon are feeling friendly with you?" You have to say yes, and you have to choose which one you want them to review. You can choose any of your current group or your boxes.
You can only enter Hammerlocke if you have the first three Pokémon badges: Grass, Water, and Fire.