Below is information on how to catch Shaymin, Dialga, Palkia and Darkrai in Pokemon Diamond or Pearl without cheating.
Method 1 of 6: Capturing Dialga
Step 1. In the game Pokemon Diamond, go to your opponent in Lake Acuity, then take the key / card from the guy Team Galactic who is standing by the satellite dish in Veilstone City, go through the headquarters, free the Pokemon in the laboratory, defeat Cyrus, and you will find Dialga
Step 2. If you have Pokemon Pearl, you need to trade with a friend or use the Action Replay code to get to Dialga
Method 2 of 6: Capturing Palkia
Step 1. Use the version of Pokemon Pearl, follow the same steps as when catching Dialga, and as a result you will find Palkia
Method 3 of 6: Capturing Shaymin
You need to attend a convention to 'legally' receive this Pokémon.
Step 1. To catch Shaymin before getting the National Dex, go to Victory Road and find the exit on the right
Follow the path until you find Shaymin.
Step 2. To catch Shaymin after receiving the National Dex, show it to any professor
Prof. Oak will offer you a choice of three Pokémon that you can catch, Shaymin is one of them.
Method 4 of 6: Capturing Darkrai
You need to attend a convention Pokémon to 'legally' receive this Pokémon.
Step 1. When you get the National Dex, go to Canalave City, talk to the sailor's wife and child, travel to the island with the sailor, and grab the quill
Then go up until you reach the house with the Harbor Inn sign., Open the door and go to bed. The battle with Darkrai will begin.
Method 5 of 6: Capturing Hitran
You need a National Pokedex for this Pokemon.
Step 1. During your first visit to the island with the Fight, Survival, and Resort areas, you can go by boat to Snowpoint City
Then go up after you land. From here you can walk to Stark Mountain.
Step 2. You will see a guy named Buck, fight him, then go straight north until you reach a cave.
3 Save first
Step 4. Then go through the maze, let Baku take the Magma Stone
Step 5. Return to the survival area and enter the house that is located along road 225
Step 6. Talk to Buck and he will give you a magma stone
Return to the place where you found this stone, Hitran will already be there.
Method 6 of 6: Hatch Evie
Step 1. Find Evie in Bebe
Step 2. Choose any of the seven Evie evolutions
Step 3. Catch Ditto on road 212
Step 4. Take Ditto and Evie's evolution to kindergarten in Solaceon Town, talk to the man outside
Or check your Day Care app; if there is an egg in between, help Evie hatch by wandering around with it.