If you’re looking to evolve certain Pokémon such as Budew, Eevee, and Buneary, they have to be at a high friendship level. Every captured Pokémon starts with a friendship level of 70 (unless they’re captured with a Friend Ball, then they start at 200), but you need to get them to 220 to evolve.
However, every in-battle level up only adds a meager five points to your Pokémon’s friendship number. You can also opt to walk with them and give them healing items such as Potions—though the growth will remain slow. Here's a faster way to level up your Pokémon's friendship in Brilliant Diamond and Shining Pearl.
1. Make them hold a Soothe Bell
A Soothe Bell will double any friendship points earned from all activities, including the ones listed below. It can be found in the Pokémon Mansion along Route 212. Talk to one of the maids in the left corridor.
2. Use them in contests and win
One amazing mechanic that returned in Brilliant Diamond and Shining Pearl are Pokémon Super Contests. Not only are they great opportunities to showcase your Pokémon's attributes but winning them also (allegedly) raises friendship.
An integral part of winning Super Contests is a Pokémon's attribute levels (Cool, Beauty, cute, Tough, Smart), and the only way to raise those is to feed them Poffins. Every Poffin flavor raises a certain attribute. For instance, Spicy Poffins raise Coolness, while Dry ones raise Beauty. Every Pokémon has a preferred flavor—and it depends on their nature. For example, an Adamant Pokémon likes Spicy food. Therefore, you would ideally enter them into a Coolness Super Contest.
3. Give your Pokémon a massage
One way to instantly increase friendship levels is to give your Pokémon a massage in Veilstone City. The masseur lives in an unsuspecting house in the west part of the area, and only offers her services once per day. The game is synced with your local time, so that translates to once every real-life day.
There's also a Pokémon masseur in the Ribbon Syndicate on the Battle Zone. However, this area is only accessible after becoming Champion.
4. Ride your bike
A Pokémon's friendship level goes up by one every 256 steps (two if they're holding onto a Soothe Bell). Reaching 220 will take forever if you just run with them everywhere, so hop onto your bike and ride in circles. The front of the ruins in Celestic Town is a great place to do this.
For more help with Pokémon Brilliant Diamond and Shining Pearl, we at Pro Game Guides have you covered.