Arceus
There are special plates in Pokémon Diamond, Pearl and Platinum. There is a plate for every type except Normal. All of the plates power-up moves of that specific type, and you can also give Arceus the plate to change his type. Depending on which plate Arceus has got, the move Judgement changes type.
In Pearl, Diamond and Platinum you may find these mystical plates Underground or in Amity square if you talk to your pokemon once in a while. You can also find one of each around Sinnoh with an inscription about the creation of Pokémon.
Plates
| Plate | Type |
|---|---|
| Draco Plate | Dragon |
| Meadow Plate | Grass |
| Iron Plate | Steel |
| Dread Plate | Dark |
| Fist Plate | Fighting |
| Flame Plate | Fire |
| Splash Plate | Water |
| Insect Plate | Bug |
| Icicle Plate | Ice |
| Earth Plate | Ground |
| Mind Plate | Psychic |
| Spooky Plate | Ghost |
| Stone Plate | Rock |
| Toxic Plate | Poison |
| Sky Plate |