If you're asking about Pictochat, then yes. Aside from the fact that the DSi has a bit more features than the DSL, you can chat with them.
The DSi can connect with all of the Nintendo DS models.
No, but you can chat on pictochat. And you can draw. Bonus.
Yes, the Nintendo 3DS can connect with the NDS lite, only if the game is compatible for both devices.
No, the Nintendo DS lite cannot play 3DS games.
The DS lite is almost exactly the same size as the 3DS.
actually nintendo has no plans for making a nintendo 3ds.
no
About the same as the DS Lite
There are several types of Nintendo DS systems ranging from the Nintendo DS, Nintendo DS Lite, Nintendo DSi, and Nintendo DSi XL. The newest version of the Nintendo DS is the Nintendo 3DS and Nintendo 3DS XL.
Yes
Yes, the Nintendo 3DS (as well as the 3DS XL and 2dS) has its own 3DS games that will not work for the Nintendo DS, Nintendo DS Lite, Nintendo DSi, and Nintendo DSi XL.
yes but 3ds games don't work on a ds lite
Yes, Pokémon Platinum was created to be a Nintendo DS game so it can be played on all of the Nintendo DS systems which includes the original Nintendo DS, the Nintendo DS Lite, the Nintendo DSi, the Nintendo DSi XL, the Nintendo 3DS and the upcoming Nintendo 3DS XL.
No. But, you will be able to play ds lite games ont the 3DS.
The 3DS does not have a slot-2, it cannot use any accessories developed for it such as the Guitar Hero addon or the DS lite rumble pack. Those are only compatible with the original DS and DS lite.