In Pokemon Black and White, the final battle of the main storyline is with Ghetsis. Ghetsis is one of the Seven Sages of Team Plasma. He is battled only once, and is battled after you defeat N.
Ghetsis team consists of: Cofagrigus lv52, Bouffalant lv52, Seismitoad lv52, Bisharp lv52, Eelektross lv52, and Hydreigon lv54.
His Cofagrigus has Toxic, Shadow Ball, Psychic, and Protect. His Bouffalant has Head Charge, Wild Charge, Earthquake, and Poison Jab. His Seismitoad has Muddy Water, Rain Dance, Sludge Wave, and Earthquake. His Bisharp has Night Slash, Stone Edge, X-Scissor, and Metal Burst. His Eelektross has Crunch, Flamethrower, Acrobatics, and Wild Charge. And finally, his Hydreigon has Dragon Pulse, Fire Blast, Surf, and Focus Blast.
After you defeat him, Alder and Cheren arrive. They arrest Ghetsis and he is never seen again.