Having completed all four of Alola’s Grand Trials, you’ll be eligible to challenge the newly constructed Pokémon League atop Mount Lanakila on Ula’ula Island. Once you’ve made all necessary preparations, fly to the Tapu Village Pokémon Center. From there, head north from the east side of the Pokémon Center.
You’ll arrive at the base of Mount Lanakila, which you may have briefly visited earlier. Approach the platform at the far end and an old friend will arrive from the stair lift. To thank you for your help earlier, he’ll give you the best present one can give: a no holds barred Pokémon battle!
Pokémon Trainer Gladion
|Silvally||55||Fire, Water or Grass|
Gladion has evolved his Golbat into the blisteringly fast Crobat. This terrifying bat can use Acrobatics to deal powerful Flying-type damage, and Cross Poison, which has a high critical hit ratio and can inflict poison. Like its previous form, you should fight it with Electric, Ice, Rock and Psychic-types. Or resist it with Steel-types.
Next up may be Zoroark, but disguised as Lucario. Unfortunately there’s no easy way to tell which one it is. So you may want to send out a Fighting-type to be safe. If it’s Zoroark, it’ll use Night Daze for STAB damage, Hyper Voice to hit resistant Pokémon, and Grass Knot to punish common Types and heavy opponents. It’ll also be holding Darkium Z.
Silvally is an evolved Type: Null that can change Type depending on the Memory Disk it’s holding. Because Gladion is smart, he’s given it the Memory Disk that’s super-effective against your starter Pokémon–so Fire if you chose Rowlet, etc. It can use Multi Attack for STAB damage, and Crush Claw, X-Scissor and Crunch for other purposes.
Finally, Gladion has a Lucario, which is an evolved Riolu. This aura warrior has high offensive stats and reasonable Speed. For attacks, it can use Aura Sphere to deal special-based STAB damage that never misses, Metal Claw for Steel-type STAB, and Quick Attack to finish off weakened foes. Fire, Ground and Fighting-types are recommended.
After defeating Gladion in his true form, he’ll give you a PP Max on behalf of Lillie. Speaking of, apparently Lillie left for Mahalo Trail on Melemele Island. From here, you’re free to use the stair lift to reach Mount Lanakila proper. But before that, it might be a good idea to take care of some unfinished business.