That patch of land on the top right hand corner of the map is where the battlezone / battle tower is. You first need to beat the elite four, get the national dex from professor Rowan (technically, from professor Oak) and then ride the ship from that city covered in snow to the battlezone. and yes, you need the national dex to be able to access the whole island because there are pokemons from the other regions.
There is a map in the Pokemon Diamond/Pearl Guide Book.
The two in pearl are Cresselia and Mesprit.
NO THERE is no second map in diamond and pearl.(that includes platnium).
Go to the place it is on the map
in the house like map
in the Pokemon league. Yes, it is but you have to go through a cave to get to it. Look on your map.
PalPark, near bottom left in your map.
Once you chase Pokemon of lake you see where they are
Theres a map on google just search it
same as diamond/pearl
Go and beat the bosses and there is a green town in the bottom of the map there is where all your Pokemon are
A battlezone is an area in which a battle is taking place.