XY In-Game Tips and Tricks

HM Slaves

All the Pokémon that can learn HM moves that are useful in-game. There are only five: Cut, Fly, Surf, Strength, and Waterfall. Rock Smash is a TM this generation.

Bidoof / Bibarel: - Cut / Surf / Strength / Waterfall; - Rock Smash
Charizard: - Cut / Fly / Strength; - Dig / Rock Smash
Corphish / Crawdaunt: - Cut / Surf / Strength / Waterfall; - Dig / Rock Smash
Dragonite: - Cut / Fly / Surf / Strength / Waterfall; - Rock Smash
Fletchinder / Talonflame: - Fly; - Flame Body as ability; useful for breeding
Hawlucha: - Cut / Fly / Strength; - Rock Smash
Tropius: - Cut / Fly / Strength; - Rock Smash; - Sweet Scent; useful for horde battles
Zigzagoon / Linoone: - Cut / Surf / Strength (Linoone); - Dig / Rock Smash; - Pickup as ability

Helpful NPCs

Name Rater: - Inside the Pokémon Center in Camphrier Town; - Cannot change names of Pokémon that were received from a trade or an event
Masseuse: - Next to the Pokémon Center in Cyllage City; - Can only get one massage per day
Happiness Checker: - Pokémon Fan Club in Laverre City
EVs Judge: - Pokémon Fan Club in Laverre City; - If your Pokémon has 510 EVs, he'll give it the Effort Ribbon
IVs Judge: - Inside the Pokémon Center in Kiloude City
Hidden Power Checker: - Anistar City. He will also give you the Hidden Power TM
Move Reminder & Deleter: - Dendemille Town. The woman is the reminder and the old man is the deleter; - They'll only do the job in exchange for a Heart Scale

Fast Money

Battle Chateau

The Battle Chateau on Route 7 is a building where different trainers can battle. The difficulty will advance through the game as you defeat players and get a new rank. You start as a Baron or Baroness and can get up to Grand Duke or Grand Duchess. You can also re-battle Gym Leaders once you acquire a higher rank.

Baron / Baroness: Pearl
Diantha: Comet Shard or Pearl String
Duke / Duchess: Nugget
Duke Hennessy: Nugget or Big Nugget
Earl / Countess: Big Pearl
Elite Four: Big Nugget
Gym Leader: Pearl String or Nugget
Marquis / Marchioness: Star Piece
Viscount / Viscountess: Stardust

Items

Prize Money Power: - Cyllage City Hotel; - Increases money earned from battles
Luck Incense: - Purchased in Coumarine City for 9,600 Poké Dollars; - Make a Pokémon hold this item in order to double the money you earn from battles
Gold Writ of Invitation: - Increases the money you earn from battling by 50%; - Can be purchased in the Battle Chateau for 100,000 Poké Dollars
Amulet Coin: - Parfum Palace in Route 6; - Make a Pokémon hold this item in order to double the money you earn from battles
Big Mushroom: - Route 14, Route 16; - Sold for 2,500 Poké Dollars
Big Pearl: - Azure Bay; - Sold for 3,750 Poké Dollars
Comet Shard: - Anistar City; - Sold for 15,000 Poké Dollars
Nugget & Big Nugget: - Dendemille Town, Kiloude City, Battle Chateau; - Lumiose City, Poké Ball Factory, Terminus Cave on Route 18; - Sold for 5,000 and 10,000 Poké Dollars, respectively
Pearl String: - Battle Chateau; - Sold for 7,500 Poké Dollars
Stardust: - Shalour City, Route 8, Route 13, Super Training, Battle Chateau; - Held by wild Staryu and Starmie; - Sold for 1,000 Poké Dollars
Star Piece: - Ambrette Town, Azure Bay, Terminus Cave in Route 18, Victory Road, Lumiose City, Camphrier Town, Route 13, Battle Chateau; - With Rock Smash: Route 8, Ambrette Town; - Held by wild Staryu and Starmie; - Sold for 4,900 Poké Dollars

Moves

Happy Hour & Pay Day: Make a Pokémon use these moves in order to double the money you earn from battles

O-Powers

These are the Pass Powers of Gen VI and they're given by Mr. Bonding, a very cheerful and flamboyant person that is found in various places.

HP restoring, Capture, Attack & Defense Power: Route 5, as soon as you receive your starter
Sp. Attack Power: Camphrier Town Hotel
Sp. Defense Power: Ambrette Town Hotel
Speed Power: Geosenge Town Hotel
Critical Power: Pokémon Center in Shalour City
Accuracy Power: Pokémon Center in Dendemille Town
PP Restoring Power: Snowbelle City
Stealth Power: Couriway Town Hotel
Prize Money Power: Cyllage City Hotel
Encounter Power: Pokémon Center in Laverre City
Befriending Power: Pokémon Center in Coumarine City
Bargain Power: Couriway Town Hotel
Exp. Point Power: Pokémon Center in Anistar City
Hatching Power: Café Introversion in Lumiose City, after getting all the other O-Powers and being stylish

Mega Stones

All the Mega Stones, listed in alphabetical order after the starters' ones. The Mega Stones that weren't handed to you can be found from 8 to 8:59pm after Professor Sycamore talks to you in order to upgrade the Mega Ring.

Starters' Mega Stones: Given by Professor Sycamore depending on the starter you picked
Unselected Starters' Mega Stones: Purchasable from a store in Lumiose City for 30,000 Poké Dollars
Abomasite: Frost Cavern in Dendemille Town after saving Abomasnow
Absolite: Kiloude City
Aerodactylite: Fossil Lab in Ambrette Town
Aggronite: Cyllage City Gym (Pokémon Y)
Alakazite: Reflection Cave on Route 11
Ampharosite: Azure Bay on Route 12
Banettite: Chamber of Emptiness in Route 22
Blazikenite: Mystery Gift; not obtainable anymore
Garchompite: Victory Road (Rock Smash needed)
Gardevoirite: After trading Diantha any Pokémon in Lumiose City
Gengarite: Laverre City
Gyaradosite: Couriway Town
Heracronite: Santalune Forest on Route 2 (Pokémon Y)
Houndoominite: Route 15 (Pokémon Y)
Kangaskhanite: Ambrette Town
Lucarionite: Given by Leader Korrina after beating her
Manectite: Route 15 (Pokémon X)
Mawilite: Shabboneau Castle in Camphrier Town
Medichamite: Laverre City
Mewtwonite X/Y: After beating or catching Mewtwo in Pokémon Village
Pinsirite: Santalune Forest in Route 2 (Pokémon X)
Scizorite: Frost Cavern in Dendemille Town behind Abomasnow
Tyranitarite: Cyllage City Gym (Pokémon X)