Deoxys is rather unique in that he has 4 seperate forms. In the 3rd generation games, these forms were spread across the different versions and whenever Deoxys was traded over, the form changed to that, recalculating the stats based upon the Base Stats of that particular Pokémon. EVs however will stay, so if you have. Due to this, you can end up getting say an ExtremeSpeed Defense Deoxys form by trading Deoxys from Emerald over to LeafGreen. In Diamond, Pearl & Platinum however, you have the ability to change Deoxys' form at will utilising the meteors in Veilstone City. To change forms in Veilstone, the stone order is this:

• Top - Speed Deoxys
• Middle - Normal Deoxys
• Bottom Left - Attack Deoxys
• Bottom Right - Defense Deoxys

Battling with Deoxys in the 3rd generation games is rather unique. As all versions are compatible, many will believe about the issue of clashing Base Stats. However, the stats and the attacks of Deoxys will remain on their respective games so even if you're in FireRed against LeafGreen, it will be Attack Deoxys VS Defense Deoxys. However, the sprite you will see your opponent's Deoxys as will always be the Normal Form. This also happens in Colosseum, but not in XD where all the forms are seen. In the 4th generation however, as you can have any of the 4 forms and change them at will, you will see that particular form in battle.

Here are the Deoxys Forms.

Normal Forme	Attack Forme	Defense Forme	Speed Forme
Base Stats: HP: 50 Attack: 150 Defense: 50 Sp. Attack: 150 Sp. Defense: 50 Speed: 150	Base Stats: HP: 50 Attack: 180 Defense: 20 Sp. Attack: 180 Sp. Defense: 20 Speed: 150	Base Stats: HP: 50 Attack: 70 Defense: 160 Sp. Attack: 70 Sp. Defense: 160 Speed: 90	Base Stats: HP: 50 Attack: 95 Defense: 90 Sp. Attack: 95 Sp. Defense: 90 Speed: 180
Games in: Ruby Sapphire Colosseum XD Diamond Pearl Platinum	Games in: FireRed Diamond Pearl Platinum	Games in: LeafGreen Diamond Pearl Platinum	Games in: Emerald Diamond Pearl Platinum

Burmy is a very unique Pokémon in that its form is ever changing between the three cloaks; Plant Cloak, Sand Cloak & Trash Cloak. These are changed dependant on the area that Burmy last battled upon.
If its on Grassy areas then it'll be Plant Cloak due to picking up leaves.
If in caves, beaches or sandy areas in general then it'll be Sand Cloak due to picking up the rocks and sand.
If in buildings or on roads then it'll become the Trash Cloak.
However, as a Burmy, it gets no use out of these changes as they are purely cosmetic, but evolve a female one with its last battle in one of those places, and it evolves into a Wormadam.

Wormadam is different to Burmy in that once it has evolved, it will keep the form that Burmy was in when it evolved so it will always be Plant Cloak for example. With Wormadam however, its learnset, stats and even its type are completely different for each form so you have to make sure you have the Burmy that you want when you evolve it. Luckily you can cancel evolution so if Burmy is of the wrong cloak at the start of evolution, just cancel and go to another place and evolve. All forms are interconnectable in Diamond, Pearl & Platinum and can be battled and traded with ease.

Plant Cloak	Sand Cloak	Trash Cloak
Plant Cloak	Sand Cloak	Trash Cloak
Base Stats: HP: 60 Attack: 59 Defense: 85 Sp. Attack: 79 Sp. Defense: 105 Speed: 36	Base Stats: HP: 60 Attack: 79 Defense: 105 Sp. Attack: 59 Sp. Defense: 85 Speed: 36	Base Stats: HP: 60 Attack: 69 Defense: 95 Sp. Attack: 69 Sp. Defense: 95 Speed: 36

Rotom is another Pokémon that obtained new forms. In Pokémon Platinum, from 28th September to November 4th 2008 in Japan and likely to happen in other regions, you have the ability to download the Secret Key over Wi-Fi. This Secret Key gives you access to a new room in Eterna's Galactic Building. In this room, there are five different items on the floor. If you have Rotom in your party and you select one of them, it will change Rotom into one of five other forms. This has Rotom possess the appliance. When he possesses the appliance, his stats are boosted and it can learn a specific attack. If you change forms, Rotom will remove this attack and learn another one so they cannot learn all of the attacks possible. All forms share the same moveset and statistics so the only difference in them is the special move that they have. The forms that Rotom changes into are as follows

• Lawnmower - Cut Rotom
• Fridge - Frost Rotom
• Oven - Heat Rotom
• Fan - Spin Rotom
• Washing Machine - Wash Rotom

Even though Rotom is in all three games, the forms are exclusive to Pokémon Platinum and as such, Rotom's forms are not in Diamond & Pearl. Like other forms, when you go into the Union Room or the WiFi Club, then Rotom will revert forms from its form into the base form, lowering its stats and forgetting its signature move. However, if you go for Battling in the Local Wireless Colosseum area, then Rotom will keep its form, its stats and its signature attack. In Platinum to Platinum battles, you will see the forms all as the forms to which they have transformed. Diamond & Pearl players however will see Rotom as its base form, despite it keeping the higher stats of its form. Rotom also reverts form when you enter it into one of the Battle Frontier facilities.

Rotom	Mow Rotom	Frost Rotom	Heat Rotom	Fan Rotom	Wash Rotom
	Leaf Storm	Blizzard	Overheat	Air Slash	Hydro Pump
Base Stats: HP: 50 Attack: 50 Defense: 77 Sp. Attack: 95 Sp. Defense: 77 Speed: 91	Base Stats: HP: 50 Attack: 65 Defense: 107 Sp. Attack: 105 Sp. Defense: 107 Speed: 86
Games in: Diamond Pearl Platinum	Games in: Platinum

Giratina is the first legendary non-event Pokémon in the game that has alternate forms dependant on the game it is on as well as external factors. Giratina's Altered Forme is found on Diamond & Pearl while it's Origin Forme is found exclusively on Platinum. It is also the first Pokémon form change that has the size and mass of the Pokémon change. In the Pokémon mythos, the Origin Forme is the form that Giratina is in in it's home dimension while it is in the Altered Forme when it enters ours, and that remains true in Pokémon Platinum. However, if you attach the item, the Griseous Orb, to Giratina, then it will remain in the Origin Forme.

Giratina is catchable in both games and as such, its form will change easily when you trade between Diamond & Pearl and Platinum. However, when you go over WiFi into the WiFi Club or into the Trade Centre, the Griseous Orb will return automatically to your bag and Giratina will revert into its Altered Forme. Over local wireless however, you have the ability to battle with Giratina in its Origin Forme. Platinum to Platinum will have the sprite showing that it is under its Origin Forme so you know exactly what you're up against. If you have a battle of Platinum VS Diamond/Pearl, then on the Diamond & Pearl games, Giratina will appear in its Altered Forme. It will keep the stats for its Origin Forme and the boosts of the Griseous Orb, but the Diamond & Pearl players do not notice it.

Altered Forme	Origin Forme
Ability: Pressure	Ability: Levitate
Base Stats: HP: 150 Attack: 100 Defense: 120 Sp. Attack: 100 Sp. Defense: 120 Speed: 90	Base Stats: HP: 150 Attack: 120 Defense: 100 Sp. Attack: 120 Sp. Defense: 100 Speed: 90
Games in: Diamond Pearl Platinum	Games in: Platinum

Shaymin is the 4th generation event legendary Pokémon that has an alternate form. Shaymin's Land Forme is found on Diamond, Pearl & Platinum while its Sky Forme is found on Platinum. Being an event Pokémon, you do not have the ability to capture it in-game without an added event item so you won't be seeing this one as often. Shaymin is the first Pokémon to have interchangeable forms that have different types and its form can only be changed by using the item; The Gracidea Flower. Shaymin's Sky Forme is also dependant on the time. It can only be utilised during daylight hours of 4am to 8pm. As soon as it hits 8:01pm if you are in the overworld, or as soon as you exit battle, it will automatically revert to Land Forme. It will also revert if you place it in the Box.

Like Giratina, Shaymin's forms have certain compatibility across the multiplayer bands. Over WiFi and in Trade Rooms, Shaymin will automatically revert back into its Land Forme. However, over local Wireless battles, Sky Forme Shaymin will remain in its Sky Forme for the duration of the battle. Platinum to Platinum players will easily be able to distinguish its forms. But like Giratina, if you battle Diamond/Pearl to Platinum, the Diamond & Pearl players will see the Shaymin in Land Forme regardless of if it is in Sky Forme or not. It will however keep the stats, typing & ability of Sky Forme so their strategy may not work due to the typing so in the interest of fairness, it might be best to tell them that its Sky Forme

Land Forme	Sky Forme
Ability: Natural Cure	Ability: Serene Grace
Base Stats: HP: 100 Attack: 100 Defense: 100 Sp. Attack: 100 Sp. Defense: 100 Speed: 100	Base Stats: HP: 100 Attack: 103 Defense: 75 Sp. Attack: 120 Sp. Defense: 75 Speed: 127
Games in: Diamond Pearl Platinum	Games in: Platinum

Unown was the first Pokémon in the games to have different forms. Unlike the aforementioned forms on this page however, Unown's forms are all purely cosmetic, despite fitting into the mythos made for Unown during GSC. There are 28 forms of Unown, each representing one letter of the alphabet and, as of the 3rd generation, 2 of them featuring punctuation marks. In Gold, Silver & Crystal there was an Unown Dex plugin to the Pokédex that allowed you to keep track of each forms. This however, has not returned. Below is a table showing all of Unown's forms.

Castform is the first Pokémon to have interchangeable forms based entirely upon attacks that it uses. With the introduction of weather attacks, a Pokémon was eventually devised that makes use of these attacks and thus further benefit it and thus Castform was created. Using the three main Weather attacks; Sunny Day, Rain Dance & Hail, Castform's visual appearance and type changes and its signature attack Weather Ball changes with these changes to make Castform much more unpredictable.

Normal	Sunny Form	Rain Form	Snow-Cloak Form
Obtained: Always	Obtained: Strong Sunlight	Obtained: Rain Pours	Obtained: Hail Hits

Cherrim is another Pokémon who's form changes when a weather attack is used. Utilising its ability, Flower Gift, if Sunny Day or a Pokémon with Drought has been used, Cherrim changes to a blooming blossom. While this does make Cherrim more susceptable to Fire-type attacks, Cherrim's Attack and Special Attack is raised. Once the sunlight ends however, Cherrim reverts back to its closed form.

Normal	Open Form

Shellos and Gastrodon are rather unique in that while they both have two forms each, the forms are not interchangeable and they make absolutely no difference to the Pokémon. The two forms of Shellos & Gastrodon indicate what part of Sinnoh that they were originally captured in. If they're caught on the West side of Sinnoh (to the west of Mt. Coronet), then they will be the pink West Sea forms, whereas if they are captured on the east side of Sinnoh. As these forms are not interchangeable, you're stuck with them, but in the routes where they reside, they are rather abundant Pokémon so you can easily get both if you do so wish. It is currently unknown if Shellos & Gastrodon that are hatched or obtained in other regions will match these conventions or be completely new.

West Sea	East Sea

Arceus, the as-of-yet un-released legendary Pokémon that sits at the end of the Pokédex (as of the 4th generation), is rather unique in that its type and appearance will change if its holding one of 16 special items. These items, when on other Pokémon, boost certain types. However, when they are attached to Arceus, they have that effect but also change its type and form to match that plate. There is one plate for each type which means 17 different Arceus forms. Arceus' signature move Judgment also is affected by these changes. However, due to these forms being dependant on both Arceus' ability and the item, its easy for an opponent to disable it with certain attacks and abilities. Below are the forms of Arceus and which items change it

No Item	Insect Plate	Dread Plate	Draco Plate	Zap Plate	Fist Plate
Flame Plate	Sky Plate	Spooky Plate	Meadow Plate	Earth Plate	Icicle Plate
Toxic Plate	Mind Plate	Stone Plate	Iron Plate	Splash Plate