Free Premier Balls from Thrifty Megamart
Location: Thrifty Megamart, Akala Island This trick is possible since you always receive a 50% coupon at the door. Speak to the lady in red and purchase at least 10 pokeballs at a time to get your free premier ball. Simply sell back your pokeballs for your purchase price and repeat. You can speed up the process by simply pressing Right on the D-Pad which will auto select 11 pokeballs.
Battle Tree Streak Rewards
After completing a streak of some number of wins at the Battle Tree, the next day on your return you will receive an item from the receptionist depending on how long your streak was:
Ability Capsule - 50-win streak.
Bottle Cap - 30-win streak.
Lansat Berry - 100-win streak.
Moomoo Milk - 5-win streak.
PP Max - 40-win streak.
PP Up - 10-win streak.
Rare Candy - 20-win streak.
Starf Berry - 200-win streak.
Oval Charm
To obtain the Oval Charm, an item which will greatly boost the rate at which Eggs appear at the Pokemon Nursery, you must first beat the game, then visit the Game Freak building and defeat Morimoto. He will give you it after the battle.
Shiny Charm
To obtain the Shiny Charm, a Key Item which will triple the rate at Shiny Pokemon are found in the game, you must first complete the Alola Pokedex. Then speak with the Game Director in Heahea City.
Trainer Passport Stamps
Stamp #1 - Official Pokemon Trainer - Receive your Trainer Passport.
Stamp #2 - Melemele Trial Completion - Complete the Grand Trial of Melemele Island.
Stamp #3 - Akala Trial Completion - Complete the Grand Trial of Akala Island.
Stamp #4 - Ula'ula Trial Completion - Complete the Grand Trial of Ula'ula Island.
Stamp #5 - Poni Trial Completion - Complete the Grand Trial of Poni Island.
Stamp #6 - Island Challenge Completion - Complete the Island Challenge.
Stamp #7 - Melemele Pokedex Completion - Complete the Melemele Island part of the Alola Pokedex.
Stamp #8 - Akala Pokedex Completion - Complete the Akala Island part of the Alola Pokedex.
Stamp #9 - Ula'ula Pokedex Completion - Complete the Ula'ula Island part of the Alola Pokedex.
Stamp #10 - Poni Pokedex Completion - Complete the Poni Island part of the Alola Pokedex.
Stamp #11 - Alola Pokedex Completion - Complete the entire Alola Pokedex.
Stamp #12 - 50 Consecutive Single Battle Wins - Obtain a 50-win Single Battle streak at the Battle Tree.
Stamp #13 - 50 Consecutive Double Battle Wins - Obtain a 50-win Double Battle streak at the Battle Tree.
Stamp #14 - Poke Finder Pro - Upgrade the Poke Finder to the final level.
Stamp #15 - 50 Consecutive Multi Battle Wins - Obtain a 50-win Multi Battle streak at the Battle Tree.
Battle Styles
Before you start a battle, you can show off your battling pose, and each style has its PokeBall throwing animation! You can change to a certain battling style by speaking to an old man in the Outer Cape located at the north of Malie City as long as you have that style unlocked. There are 8 different Battle Styles total.
Elegant Style - Speak to the old man at the Malie City Outer Cape.
Girlish Style - Defeat Lana in a battle in Konikoni City.
Idol Style - Clear Master Rank in the Battle Royal.
Left-Handed Style - Defeat Ilima in a battle in Hau'oli City.
Passionate Style - Get 50 consecutive wins or higher in the Battle Tree.
Reverent Style - On Sun, defeat Kiawe in a battle near the Thrifty Megamart in Paniola Town, or on Moon, defeat Mallow in a battle in Lush Jungle.
Smug Style - Defeat Gladion on Mount Lanakila before the Elite Four.