What Exactly Does The Special Attack/defence Mean On Pokemon Platinum?

Special attack relates to a Pokemon's power in terms of magic moves and Special defence relates to it's ability to reduce damage from magical moves. Obviously, the most this number then the more your magical attack will do or the less you will take from it.

The way to determine if a move is magical or physical is if once you use it it seems to have a bold move. This can be seen in 'Body Slam', 'Giga Impact' and 'Tackle' though if you cannot tell yourself, go to your Pokemon skills under "Summary" in the drop down menu and selecting over the move. Once you have selected the move, under category it will have either a red rectangle with a yellow star, purple rectangle and violet/light purple ovals or a white rectangle with yin-yang sign in it. The purplish rectangle means magical, red rectangle means physical and white rectangle means spells.

Special attack/defence only effects magical attacks to and from your enemy.

Hope this helps you mate.

Sp attack is when a move of your own type is more powerfulle.g. If your fire type and you have a have a high sp attack state fire moves will be more powerfull.sp def helps take damage from moves that are super effective against youe.g. If you   were a water type it would help protect you against electricity and grass

When you go to Summary on your Pokemon and go to the moveslist tab. Press button so you can see info on the move. The ones with a orange background and a yellow flash is attack.

The ones with like a purplish ripple is sp atk. That doesnt really answer your question because I don't know what they mean but I know what they are :P

I think it's for TM and HM moves you teach it.