Want to know. Thank you in advance.
What Ghetsis wants to do is to freeze Unova using Kyurem, and steal every Pokemon, rather than releasing them.
Source: I've played W2 and this is what he wants...
Same as BW1.
Rule all Pokemon.
http://bulbapedia.bulbagarden.net/wiki/Ghetsis
In Pokémon Black and White 2, Ghetsis turns out to be once again: > Ghetsis is behind TeamPlasma's activities. This version of Unova's villainous team > is not attempting to release Pokémon, but instead take over Unova. He > wants to freeze Unova so that Team Plasma can steal every Pokémon in > the region. He has appointed Colress as the new official boss of Team > Plasma and recruited Zinzolin to help him. After being defeated at the > Giant Chasm he suffers a mental breakdown and is escorted away bya > memberofthe Shadow Triad. Later, in Icirrus City, the Shadow Triad > reveal that Ghetsis has lost heart and is no longer capable of any > further criminal deeds.
He is insane in BW2.
To take over the world like any other team.