There are tons of apps to be found in Pokemon Brilliant Diamond and Shining Pearl. One such app is known as the Pokemon History app. This app is used to see the Pokemon you have recently caught. When you open the app, you will see a picture of each of the Pokemon in your catch history. Here's how to get this app.
Before you can get this app, you need to get your Poketch app first. You will get this item at the beginning of the story by answering the questions posed by the clowns in Jubilife City. After obtaining the Poketch, you will need to defeat at least two of the gym leaders in the game. These Gym Leaders are found in Ore City and Eevopolis.
Later in the game, you will head to Hearthome City and be directed to Veilstone City. To get there, you will need to take Route 209 which will take you to Solaceon Town. Prepare yourself before embarking on the journey through Route 209 as you will have to face several trainers along the way. Once you reach Solaceon Town, talk to the NPC ranger to the left of the Pokecenter. He will tell you the story before giving you the new app.