Unlock the National Pokedex
Beat the Elite Four and after the credits Professor Juniper will give you the National Dex.
Power Hold Items
All of these items can be purchased at the Battle Subway
Power Weight: Adds 4 HP EVs after every battle, halves the speed stat.
Power Bracer: Adds 4 Attack EVs after every battle, halves the speed stat.
Power Belt: Adds 4 Defense EVs after every battle, halves the speed stat.
Power Lens: Adds 4 Special Attack EVs after every battle, halves the speed stat.
Power Band: Adds 4 Special Defense EVs after every battle, halves the speed stat.
Power Anklet: Adds 4 HP EVs after every battle, halves the speed stat.
Macho Brace Hold Item
The Macho Brace can be found in Nimbasa City, from a man standing in the Eastern gate of the city.
This hold item will double any EV points the Pokemon gets in battle but will halve its speed stat.
Leftovers Hold Item
You can find the Leftovers hold item in a trash can under the Village Bridge between Route 11 and Route 12. Use the Dousing Machine to pinpoint it.
This item restores 1/16th of a Pokemon's health every turn.
Black Sludge Hold Item
There is a 5% chance that a wild Trubbish/Croagunk/Toxicroak will be hold this item when you encounter them. Wild Garbodor have a 50% chance of holding this item.
This item will restore 1/16th of a poison type Pokemon's HP every turn. It will damage any other Pokemon type if they hold it.
Big Root Hold Item
This item can be found in the Pinwheel Forest. It increases the amount of HP the user gets from successful Energy draining moves like Leech Seed.
There is also a 5% it can be found on a wild Lileep or Cradily.
Lucky Egg Hold Item
Professor Juniper will give you the Lucky Egg once you arrive at Chargestone Cave on Route 6. It is extremely useful as the Pokemon holding it gains extra XP for every battle they're involved in.
Battle Company 47F, Castelia City
The scope lens is a hold item that boosts a Pokemon's critical hit ratio. It can be found on Floor 47 in the Battle Company in Castelia City.
Karrablast and Shelmet Evolution
Escavalier and Accelgor
To evolve Karrablast and Shelmet, trade one for the other with a friend. The Karrablast will evolve into Escavalier and the Shelmet will evolve into Accelgor. Escavalier is very slow, but sturdy, while Accelgore is very fast but with low defense.