Q&A for How to Catch Dialga and Palkia in Pokémon Platinum

If you are playing in Platinum, you can get both. If you're playing in Peal/Diamond, you can only get one.

Beat the elite four, go to Canalave and go into the house in the bottom left, next to the boat that took you to Iron Island. There should be a boy there who is trapped in a nightmare and, when you speak to him, Cressellia will be available. Go to the sailor on the jetty and he will tell you about getting a lunar wing, so go to Halfmoon Island. Once you get it, Cresselia should be wandering around.

Catch and train more Pokemon, train to level 80 and/or teach Empoleon stronger moves.

Give the amulet coin to the Pokemon you plan to use in each battle of the Pokemon league. Go through it several times, and you'll rack up money fairly quickly.

You should use a Grass-type Pokémon, preferably one that knows Grass Knot, against Bertha. Many of her Pokémon are heavy and possess a 4x weakness to Grass attacks, making this strategy highly effective.

If you have Platinum, you can get both. But if you have Diamond or Pearl, only one of the two.

Route 207 (Oreburgh City), and Route 208 (Hearthome City). You will need a bicycle to go there if you would approach it from Route 207 (you will need to go up the muddy incline with bicycle), and you will need to go through some grass if you decide to go there from Route 208.

Yes. You can get it during the main story line, when you go up to Spear Pillar.

No, you have to complete story mode first, then you can catch Dialga and Palkia.

Levels 47-55 to beat it easily, save before you fight so if you accidentally beat it, you can quick restart to try again .

After getting the Nationel Dex, go to Route 214. There is the Spring Path. Save the game.

Yes. After beating the game and getting the National Pokedex (not all 493, this means the upgraded dex), you'll be able to go to a place called Turnback Cave. In here, you can find Giratina.