Friendship is an important feature in Pokemon Brilliant Diamond and Shining Pearl, if you want your partners to obey you in battle and also to evolve certain mons.
There are a handful of Pokemon who can only evolve if your Friendship level with them is high enough. It is important to train those partners properly and make sure they are utilized to increase their Friendship.
Brilliant Diamond and Shining Pearl gives players a few different ways to increase Friendship levels of Pokemon. Certain items, Poke Balls, and actions will raise the Friendship level of your partners.
Different ways to increase Friendship level in Pokemon Brilliant Diamond and Shining Pearl
There are two types of Poke Balls in Pokemon Brilliant Diamond and Shining Pearl that will increase Friendship level. Those Poke Balls are the Friend Ball and the Luxury Ball.
If you catch a creature with either of those types of Poke Balls, they will not only be added to your collection and Pokedex, but they will automatically have a higher Friendship level from the get-go.
The Soothe Bell is an item that can be found in the Pokemon Mansion. This item can be held by a Pokemon and whenever they are used in battle, they will receive a boost to their Friendship level.
The normal Friendship level of battling will be greatly increased by this item. You can only give it to one Pokemon at a time, though, so be sure to change it out when you need another's Friendship level increased.
Using your Pokemon
Simply battling with a Pokemon, and winning, will increase the Friendship level. This is a normal activity within the game, so just battle with whatever partner you want to raise the level of.
Also, walking around or riding your bicycle with that Pokemon will raise their Friendship level every so often. This counts as spending time with them and showing affection.
Trainers can get their Pokemon a much-needed spa day in Veilstone City. There is a house located on the west side of the city that gives massages, but only one per day is allowed.
It is a slower method to soley rely on, but it does provide a great increase to Friendship level every time a massage is given. Pair this with some of the other options above and max Friendship level will be reached in no time.