Can someone tell me where can I dowload the full openings and endings of Pocket Monsters Diamond & Pearl anime (the japanese version, of course, not the english one)?

They're in there...somewhere. You've to look for yourself.

Thread 59963

Together/Kimi no Soba de single
http://www.mediafire.com/?cm2wno9mybm

Together Kimi no Soba de 2007 single
http://www.mediafire.com/?fmbinzdming

High Touch - Ashita wa Kitto 2008
[will have to search through my stuff and put together the upload]

Kaze no Message - Kono Yubi Tomare 2008
http://www.megaupload.com/?d=0LSLUYFI

Crystal Kay - ONE Pokemon Edition (Pikachu Edition) 2009
http://www.4shared.com/file/56834152/cce0299f/Pokeplusnet_-_Crystal_Kay_-_ONE__Pokemon_Edition_.html
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that's only some of them... try searching in the Pokemon forums, they may have the rest (excluding the newest that came out a few days ago... unto single).