Instructions
Defeat the Elite Four and encounter all 150 native Pokemon in "Pokemon Diamond" to receive the National Pokedex at the end of the main story. Visit Professor Rowan in Sandgem Town to pick up the National Pokedex.
Enter the Turnback Cave on the far side of Sendoff Spring. The opening to Giratina's lair is on the far east of Route 214; reach it by walking through a path in the trees. Surf across the spring's waters and enter Turnback Cave.
Study the layout of each room to navigate Turnback Cave. Each room has three exits and they are presented randomly. Leave the room with the odd-numbered feature that breaks the pattern of the room to progress through the cave. For example, if a room has two rocks on each side of the room and four rocks on another, exit through the portal closest to the four rocks.
Pass three rooms with towering pillars on the way to Giratina's chamber. If you arrive in a room with a pillar, that means you are making correct choices along the way. Save the game once you find Giratina.
Walk up to Giratina and attack it with Ghost, Dragon, Ice and Dark-type attacks to weaken it. Use Pokeballs on Giratina when its health bar lowers to the red area to capture it. All of Giratina's stats are exceptionally high and it is resistant to being captured in a Pokeball, so have patience when attempting to catch the ghost dragon.