After you’ve defeated N of Team Plasma, Alder, the Elite Four Champion, will arrive to congratulate you on your victory. Ghetsis will arrive, telling you the full story about Team Plasma, since you managed to win against N. He says that there is no liberation of Pokemon, but to make people naďve enough to believe that letting go of their Pokemon means making the world a better place. When everyone releases their Pokemon, no one will resist the rule of Ghetsis and Team Plasma, especially now that a legend has been caught and tamed. He further explains how N was just a tool of his plan, and that now it has been executed successfully, N is of no more use. You will now face off with Ghetsis for the true battle of Unova, but not before N heals your Pokemon.
Ghetsis poses a huge threat, and his Pokemon are just as tough to defeat. Like the Elite Four, five of his Pokemon stay at a consistent level 52. His last Pokemon is at level 54, so training your Pokemon to that point should be enough to emerge victorious. Remember, if you’ve picked to use your legend, it will be a lot easier to use in battle, although if you enjoy EV training legends, it may mess up its Effort Values. When the battle starts, Ghetsis will send out Cofagrigus, which has a habit of using Toxic and then Protect. If you have any special attackers, don’t be afraid to use them, as Cofagrigus is slow, but a good physical defender.
One of his next Pokemon is Eelektross, which is an Electric-type. Don’t use a Ground-type Pokemon, because its Ability is Levitate, making it immune to those kinds of moves, and eliminating its only weakness. It is not too hard to defeat it in two hits, but you should use speedy Pokemon in order to get through it.
Ghetsis’ third Pokemon is Bisharp, which can be easily overcome with a Fighting-type move. If you don’t have any of those, using a Water-type can help, since it has a lower Special Defense, and none of its moves will score a supereffective hit against your Water-types.
Next is Bouffalant, which is a devastating physical attacker. If you don’t want to get swept with Earthquake, try using a Flying-type, which will gain immunity. Keep in mind that Ghetsis has Full Restores in case his Pokemon’s HP reach dangerous levels.
His fifth Pokemon is Seismitoad, which, like Bisharp, has a double weakness, but this time, to Grass-types. Use a fast Grass-type if possible, because it has Sludge Wave. None of its other moves should pose a threat to a well-balanced Grass-type.
Finally, Ghetsis’ last Pokemon is Hydreigon at level 54, which is irregular, since Deino evolves into Zweilous at level 50, and again at level 64. It has moves to cover every type except for Fighting, so try to use a Fighting-type move. Once you win, you will have officially saved Unova from the hand of Team Plasma.