Battle Tower
Introduced in Pokemon Crystal, the Battle Tower is a place for trainers to test their skill against tough opponents. In Pokemon Diamond and Pearl this is the same. There are a few changes though. There will only be LV50 Pokemon battles here, but even if your Pokemon are over LV50, they can still enter; their level will just be temporarily reduced back down to 50, but after finishing the challenge, they'll be back to normal.
Like in other games, you get Battle Points after clearing the challenge. These can be traded for some rare and valuable prizes.
Legendary Pokemon
Like in the Battle Frontier, you are not allowed to enter Pokemon like Mewtwo. Below is a list of Pokemon that can't be entered.
Mewtwo
Mew
Lugia
Ho-oh
Celebi
Groudon
Kyogre
Rayquaza
Jirachi
Deoxys
Dialga
Palkia
Manafi
Fione
Darkrai
Sheimi
Aruseus
Once you enter, you'll see three counters. The far right one is for Wi-fi and battles over the Internet. Here, you can register a trainer over the Internet and you can face them and their Pokemon in the Battle Tower randomly.
Single Battles
The center door is for the normal one-on-one and two-on-two battles. This works exactly like the Battle Towers in the 3rd generation games; the difficultly level increases for each row of victories. Like in Pokemon Emerald, the leader of the area comes out to challenge you; this is only in single battles though.
The Tower Tycoon Palmer will challenge you after 20 straight wins. Below are his Pokemon.
Rhyperior
Milotic
Dragonite
After 48 straight victories, the Tower Tycoon will challenge you to a battle again. Below are his Pokemon.
Heatran
Regigigas
Kuruseria
Double Battles
The final booth is for doubles battles. Here is where you can team up with your friends or trainers around the world in a double battle either against the computer or somebody else. If you don't have a partner to team up with, you can head into a room full of trainers. These trainers though might look familiar to you. They are trainers that you have helped out and that have teamed up with you. They will have a whole heap of Pokemon. Below are the people and their specialty.
Cheryl from Eterna Forest
She uses Pokemon with high HP and high Special Attack
Snorlax
Espeon
Umbreon
Porygon2
Blissey
Milotic
Latias
Latios
Gastrodon
Porygon-Z
Kurseria
Mira from Wayward Cave
She uses Pokemon with high Special Attack
Alakazam
Gengar
Zapdos
Espeon
Gardevoir
Latios
Roserade
Magnezone
Magmortar
Togekiss
Glaceon
Porygon-Z
Riley from Iron Mountain
He uses Pokemon with high Attack
Poliwrath
Machamp
Rhydon
Gyarados
Ursaring
Tyranitar
Blaziken
Breloom
Slaking
Hariyama
Medicham
Absol
Salamence
Metagross
Rampardos
Lucario
Toxicroak
Rhyperior
Mamoswine
Regigigas
Marley from Victory Road
He uses Pokemon with a high Speed
Dugtrio
Electrode
Starmie
Aerodactyl
Crobat
Sceptile
Swellow
Ninjask
Weavile
Buck from Stark Mountain
She uses Pokemon with high Defenses
Umbreon
Forretress
Steelix
Shuckle
Skarmory
Regirock
Regice
Registeel
Bastiodon
Rhyperior
Probopass
Dusknoir
Kuruseria