Cheats:
Make 'em glitter!
If you rub your gym badges with your stylus, you can polish them to a glimmering glow. Try it! (You can also play simple melodies on them. Useless but entertaining.)

30 minute time limit
When you go inside void caused by this glitch you have 30 minutes to explore.

Walkthrough wall glitch
In the Jubilife TV station, where you can decorate pokemon, talk to him on the side. When he asks what pokemon to decorate, press the opposite direction of which you are facing and you will enter room through wall.

pikachu's volt tackle
to get pikachu to learn volt tackle you have to get a light ball from a wild pikachu that may take a bit. when you have the light ball get a female pikachu and ether a male pikachu or a ditto. the pichu that comes from the egg should know volt tackle.

what time of the day to get Rotom
The time of the day to get Rotom is at 8:00pm-4:00am. If you need anymore help send me a request for help.

form change
go to Veilastone city with Deoxys and look at a meteorite and he will change forms.

To Catch Giratina
After you get the National Dex,Via,Seeing all the pokemon in Sinnoh,Then going to Prof.Rowan.A new area will appear.The spring path. It is located near route 214. Go further into the path and find Sendoff spring.Go even deeper to Find Turnback Cave. Inside there are Bronzong and Haunter about level 50.and, of course the Legendary,Giratina. To Find it,pass three Pillars with scripture on them. there are pointers leading to them. After you find all 3 pillars,go where the pointers lead you to find Giratina. (Note:It is very foggy in there,You should bring a pokemon that knows Defog.)

To Get Arceus
To get Arceus, you need to go to Hearthome city, and go into the Pokemon Center. Then, you will see a man. If you talk to him, he will give you the Azure flute. To get him to show up, you need to have all 8 gym badges, beat the Battle Tower, and defeat Dialgia. Onec you do this, he will appear and give you the flute. Then, go to the top of Spear Pillar, and the flute will play. A flight of stairs will appear, and you need to go up it. As soon as you walk onto the platform, you will fight Arceus at a level 80! I hope you saved your master ball for this battle. If not, lower him down to a low health, and throw an ultra ball at him. Eventually, he will be tried, and give up. You need about 70 ultra balls if you want to catch him. Also, other pokeballs are suggested. Once you catch him, you have one of the strongest Pokemon in Pokemon Diamond. Good job!!

Change Deoxys' Form
Go to Veilstone City. You will find four meteors. If you talk to one with Deoxys in your party, It will change forms. The best form is Attack Form.