To reach the Vast Poni Canyon, you must head north from the central crossroad in Ancient Poni Path. The easiest way to get there is to fly to the Ruins of Hope, then cut through Poni Breaker Coast. As you approach the entrance to the canyon, you’ll be stopped by the unrelenting remnants of Team Skull.
Team Skull Grunt
Apparently this Grunt thinks that a single Ekans can stop someone who laid waste to Po Town. Actually, it gets even better as this Ekans does not have a single attacking move…
Team Skull Grunt
This the "everything and the kitchen sink" strategy. Fomantis is trivial since it’s unevolved and thus outclassed by your fully evolved Pokémon. It can use Solar Beam, but it’s so weak and slow, it shouldn’t survive to use it on the second turn–and even if it does, the damage is not particularly strong.
Mareanie is slightly trickier, but again unevolved. It can use Poison Jab for STAB and Recover to restore HP. Tackle it with Electric, Ground or Psychic-types. Houndour is in a similar boat. This demonic dog can use Flamethrower and Foul Play. Flail it with Water, Ground, Rock or Fighting-types.
Golbat is evolved, although not fully. It can use Venoshock and Leech Life. Electric, Rock, Ice and Psychic-types are its bane. Finally, the Alolan Raticate can use Double Edge for STAB, and a combination of Endeavor and Sucker Punch to annoy. Whack it with Fighting, Bug or Fairy-types.
Once play-time is over, Plumeria arrives to take her children home. She’ll also give you her precious Poisonium Z , hoping it’ll be useful during your upcoming battles. After the dust has settled, Lillie will heal your party, before awaiting your next move. There’s a lot riding on your shoulders, so without further ado: to the canyon!
Vast Poni Canyon
To reach the altar dedicated to Alola’s Legendary Pokémon, you must cross this harsh and unforgiving canyon. From the entrance, approach Hapu and Mudsdale by the large, leafless tree. Before you’re allowed to continue, the Ultra Recon Squad will appear and give you one final challenge.
Ultra Recon Squad Dulse/Soliera
It really hasn’t been that long since you last fought Poipole. Although it’s two Levels higher, it has the exact same moves, so you can repeat the strategy you used last time. For reference, it can use Poison Jab for STAB damage, and Fell Stinger to hurt Psychic-types and greatly enhance Attack if it KOs the opponent.
When it’s not dealing damage, it can use Toxic to inflict deadly poison, and Nasty Plot to boost Special Attack. Its trainer may also use an X Sp. Def to boost its Special Defense. Ground-types are ideal, although Psychic-types can be considered if they’re not frail, and Steel-types for resisting damage.
Show the Ultra Recon Squad the extent of your determination and they’ll happily step aside and let you save the world. Once you’re left to your own devices, head for the tree branches to the left of the cave that Lillie is standing in front of, and crawl through the space underneath. On the other side, grab TM93 Wild Charge , before crawling back.
Finally approach Lillie in front of the cave and she’ll give you a Max Revive , as well as restore your party to peak condition. The road beyond the cave is long and treacherous, so make sure you have all the items you need. If necessary, you can fly back to a Pokémon Center and easily return here from the nearby glide spot.