Upon your arrival, you’ll be greeted by the two Ultra Recon Squad members who didn’t travel to Alola.
To proceed, head all the way north towards the base of Megalo Tower, towering in the distance. Due to the danger posed by Necrozma, the city streets have been closed off and all the civilians are hiding inside. After being warned, go through the door at the top of the steps. Inside the tower, you’ll emerge in an elevator that will take you straight up to the top.
At the top of the tower, run up the metal staircase to reach the roof where Necrozma is awaiting.
In its true form, Necrozma has overwhelming offensive stats and Speed. To add insult to injury, it will receive a boost to all of its stats, making it an extremely oppressive Pokémon to fight. Do not be surprised if Ultra Necrozma one-shots most of your Pokémon before they even get a chance to act, especially if they’re of equal Level or lower.
In terms of attacks, it can use Photon Geyser and Dragon Pulse to deal massive damage thanks to STAB and its obscene stats. If facing Ice and Fairy-types, it may use Smart Strike to hurt them. Finally it has Power Gem, just in case, and to beat down Incineroar. Also note that its Neuroforce Ability makes its super-effective attacks stronger.
For this battle, Dark-types are ideal, to avoid the insane damage from Photon Geyser. Meanwhile Steel-types are great as they resist all of Necrozma’s attacks. Special tanks in general are also really good. As soon as the battle begins, we strongly recommend using an X Sp. Def to boost your Pokémon’s Special Defense.
If your Pokémon can survive Photon Geyser, you can spam healing items until it runs out of PP (it only has 5). From there, the battle should be a lot more manageable, since you only have to deal with the weaker Dragon Pulse and the two moves that don’t have STAB. Necrozma cannot heal, so all you have to do is keep attacking until its out of HP.
Back to the Drawing Board?
Now it’s entirely possible that none of your Pokémon can take a hit from Necrozma. In that case, you should leave Ultra Megapolis and go back to train your Pokémon, or devise another strategy. One thing you could try is using Toxic (obtained from the Aether Paradise docks) to KO Necrozma within 6 turns.
That said, you still need a Pokémon that can take a hit in the first place, so they can use Toxic. If you’re really struggling, go and catch a Zorua from the grass in Trainer’s School. Place Zorua are the front of your party and teach it Toxic. Then place a Fighting or Poison-type in the last slot of your party. This could be the traded Hawlucha from Route 2.
If you haven’t figured it out, when Zorua enters battle, it will take on the appearance of the Fighting or Poison-type, which will cause Necrozma to attack it with Photon Geyser. However the attack will fail since Zorua is a Dark-type. This will give you an opportunity to use Toxic with Zorua and then stall with Protect or whatever.
Triumph against this maddenly powerful foe and peace will return to Alola and the worlds beyond! To thank you for saving their world, the Ultra Recon Squad members will give you Poipole, the Poison-type UB that you fought multiple times. In addition, they will give you the option of using Solgaleo or Lunala during Ultra Warp Ride.
Afterwards, you’ll be brought back to the Altar of the Sunne/Moone, where the curtains will close on this episode. In acknowledgement of your efforts, you’ll receive 3 Beast Balls that can be used to capture the UBs found in Ultra Warp Ride. For your information, you can buy more from Aether Paradise’s entrance area.
Once everyone has left, Captain Mina will come visit the altar. Despite missing all the fun, she’s here to give you something special: an invitation to her newly thought up island trial. If you’re ready, accept her offer to travel straight back to Seafolk Village. Otherwise, you can head there and visit the Whiscash-shaped boat yourself.
Tales of Courage
Having visited Ultra Megapolis, you’ll now have enough tales of courage to tell the young boy in the Royal Avenue park (to the east of the Pokémon Center). In total, he needs five tales before he’s fully inspired:
After telling him one tale, you need to exit the area (for example, via the nearby Pokémon Center) before you can tell him the next one. Once he’s heard all five stories, he’ll challenge you to a Pokémon battle straightaway.
This evolved Rockruff has exceptional Attack and Speed, but mediocre bulk. For attacks, it can use Stone Edge to deal devastating STAB damage, Crunch to hurt Psychics and Ghosts, Rock Climb to potentially cause confusion, and Scary Face to lower Speed. Coming from Ultra Necrozma, this should be an easy win.