How do you make Palkia and dialga your friend on PokePark Wii?

To make Palkia and Dialga your friend in PokePark Wii, you need to first complete specific tasks to unlock them. After encountering them in the game, you must engage in a friendship mini-game where you can earn their trust. Successfully completing their challenges and showing your skills will increase your friendship level with them. Once their friendship meter is filled, they'll become your friends, allowing you to play as them in the game.