How do you change Rotoms form in Pokémon White 2?

Changeable?: No

Method:
Basculin is the first Pok�mon you'll encounter with different forms. This Pok�mon has two forms, the Red Stripe Form and the Blue Stripe Form. These forms are not interchangeable and are dependant on its appearance at capture. The Red Stripe form is the form found during play on Pok�mon Black and the Blue Stripe form is the form found in White. However, you have the ability to find the other forms in the other games through use of the new Wild Pok�mon encounter method where Pok�mon will appear randomly it bits of water.
In addition to the change of appearance, the forms can have different abilities. While their Dream World ability, Mold Breaker, and their second ability, Adaptibility remain constant between both forms, each form has a different potential ability based on the version. It is currently unknown as to what specifically changes the ability as both forms can have Reckless and Adaptability, but Rock Head is possible to get in some Basculin and is obtainable by the Blue Stripe Form within the trade in Driftveil City. However. In addition to this, each form has a different possible hold item, at a 5% rate of having the item.

Changeable?: Yes

Method:
Darmanitan's form change is unique in that not all Darmanitan have the ability to do it. If you have evolved a Darmanitan from Darumaka, then you will not be able to get his alternate form. To get this form, you either need to get a Darmanitan off of the Dream World, or get one of the six that are sitting outside the Relic Castle in the Desert Resort.
These Darmanitan have the ability; Zen Mode which, when Darmanitan's Hit Points get to be less than 50% of their full value, Darmanitan will change into Zen Mode. This change is radical and changes both Darmanitan's stats and his type.

Changeable?: Yes

Method:
Deerling and its evolution Sawsbuck each have four different forms. These forms are dependant solely upon the season that is currently in play. As the Season is not controllable by you, you have no control over what form these Pok�mon take. That said, if they are in the box at the time of the seasonal transition, they will keep their current form until the next change. The forms have no difference in learnsets or stats but are merely an aesthetic change to show off the new mechanic of the seasons.

Changeable?: Yes

Method:
Meloetta is an upcoming event Pok�mon and also has two different forms. These forms differ in both stats and type. To change the form of Meloetta, you need to take it to the caf� in Castelia City where you'll meet a character who will teach it a brand new move. This move, Ancient Voice, will allow you to change Meloetta's form at will, however it only changes when its used in battle.

Changeable?: Yes

Method:
Deoxys' four forms make a return within this game. When you have sent Deoxys over via the Pok�Transfer in Route 15, you can take it to Nacrene City where a meteorite is on display in the museum. Interact with this meteorite with Deoxys in your team and you'll be able to change its form. You can't select the form, but it does cycle through them in this order; Normal Forme -> Attack Forme -> Defence Forme -> Speed Forme

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

Changeable?: Yes

Method:
Rotom's five alternate forms make a return within this game. When you have sent Rotom over via the Pok�Transfer in Route 15, or received it in the trade in the same route, you will be able to take Rotom with you to the Department Store in Route 9. In this store, there is a room with multiple storage boxes. Interact with this box and you'll be able to change your Rotom's form. These Rotom all have special attacks that can only be used while in that form and, as a new addition, they all now have a new type replacing the Ghost-type in their new forms.

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

Changeable?: Yes

Method:
Giratina's alternate forms are also present within this game. After you have defeated the Elite Four, when you go onto the Cycling Road in Route 16, you will encounter the members of N's squad known as Dark Trinity. Out of apology, they'll give you items; the Adamant Orb, Lustrous Orb and most importantly, the Griseous Orb. With this item, you can attach it to Giratina and Giratina will change its form to its Origin Forme

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

Changeable?: Yes

Method:
Shaymin's alternate forms are also present within this game. After you have defeated the Elite Four, when you go to the Lacunosa Town Pok�mon Centre with a Shaymin from an event that you've transferred over from the fourth generation games, talk to the lady here and she will give you the Gracidea key item. This item will change Shaymin's form between 5am and 8pm each day.