No, you cant. Thats why they made the Dream Radar.
Landorus can only be in its Therian form if it was caught in the 3DS downloadable game Dream Radar. To change it to its Incarnate form, you must bring it ints Therian form to the Abundant Shrine. You will receive an item called the Reveal Glass that allows you to switch it, Thundurus, and Tornadus into their Incarnate forms and back.
After catching Landorus in the Pokémon Dream Radar application and transferring it over to Pokémon White 2, you will need to take it with you to the shrine in the Abundant Shrine and you will be given the item called the Reveal Glass. Use the Reveal Glass on Landorus from your bag and it will change Landorus to its Therian Forme.
Take Tornadus and Thundurus to Abundant Shrine. A wild Landorus will appear.
In Pokémon Black 2, in order to get the item that is called the Reveal Glass, you will need a Landorus while it is currently in its Therian Forme. The only way to receive Landorus while it is in its Therian Forme is to get the Dream Radar from the Nintendo 3DS eshop and then find and capture Landorus in the Dream Radar and then you can send Landorus over to Black 2 and it will remain in its Therian Forme, you will then need to put it in your party and take it with you to the Abundant Shrine and the guy there near the Shrine will give you the Reveal Glass.
Get both Tornadus and Thunderus to the Abundant Shrine and it will appear
Landorus will be at Level 70 once it appears at the Abundant Shrine in Pokémon Black and Pokémon White.
you need thundurus and tornadus ( traded from pkmn black) and then go to the abundant shrine and landorus is there lv.70
In Abundant Shrine (Bring Landorus Therian Forme).
Landorus is found at the back of the abundant shrine, however, it will not appear unless both tornadus and thunderus are in your party.
Once you catch Tornadus, and get Thundurus from a trade, then you can visit the shrine to make the third member of the trio, Landorus, appear.
In order to receive the Reveal Glass in Pokémon Black 2 and Pokémon White 2, you will need take Landorus in its Therian Forme to the Abundant Shrine on Route 14 and make your way up to the actual Shrine itself in the area and a player will give you the Reveal Glass item once it sees that you have Therian Forme Landorus in your party.
You have to take Landorus to the Abundant Shrine, on Route 14. Doing so will give you an item that lets you transform Thundurus, Tornadus and Landorus.