Unlike all the previous Pokemon games when you had to defeat the Champion and complete the main storyline, Team Plasma has stayed in the plot until the end of the game. After you defeat the Elite Four and take the statue down, you will find N next to Alder. N says that you will have to battle him in his castle, which is revealed to be rising around the Pokemon League in a custcene.
You will have to battle N, who is waiting on the top floor. The entryway is blocked by the Seven Sages, but all of the gym leaders except the Striaton Gym help block them in order that you may pass. First, you can heal your Pokemon in one of the rooms by a nurse who is a part of Team Plasma. Make sure you go into every room and find all the items, because this will be the only time you can be in his castle. Ghetsis’ three assistants will then show you N’s room when you reach the second floor. It is kind of predictable, seeing as his childhood room was full of toys. But Ghetsis’ assistants give you something to think about: why did N join Team Plasma?
When you reach the top, you will find N waiting for you. He says that he has captured the legendary dragon, which will be either Reshiram or Zekrom, depending on your game. N tells you a story of why he joined Team Plasma, and more of his opinions on the relationship between Pokemon and humans. He also tells you his ideal, which is to revolutionize the Pokemon world so Pokemon will be separated from humans. N also recognizes your ideal, which is to save the world from Team Plasma. After this, Reshiram or Zekrom will appear in a custcene behind N, and N will challenge your ability to defeat Team Plasma by challenging you to capture it.
You can save the game if you want, and have unlimited chances to capture it, but proceeding with or without capturing it doesn’t really matter, since it will reappear in Dragonspiral Tower if you accidentally KO it. If you capture it, you will be given the option to use t in your battle, or send it to your PC Box. I would suggest using it, since N’s first Pokemon will be your legendary’s counterpart. Plus, your legend will have that signature move with a lot of power that gains Same Type Attack Bonus. To ensure a fair battle, N will heal your Pokémon before the fight for both ideals begin. N is relatively easy to defeat if you have Pokémon that are at least level 50. His lineup consists of either Reshiram or Zekrom, Vanilluxe, Zoroark, Carracosta, Archeops, and Klingklang. You may think that once you defeat him, you have saved Unova, but that’s not all to this interesting story.