you cant use the 3DS charger for the DS/DS Lite, but you can use the 3DS charger for the DSi and the same with the DSi charger, you can use it for the 3DS.
If they were specially designed for the 3DS, no. There is a small tab jutting out of the side of 3DS games making them unplayable on a DSi. Even if you could fit the cards into a DSi, they would not work because they use 3D technology the DSi cannot utilize. DSi games will be playable on the 3DS though.
yes. a dsi is the same as a normal ds but with a camera.-------------------------------------------------------------------------------You can use the same codes from the DS to the DSI, but you cannot use a DS Action Replay for the DSI, you have to use a DSi Action replay, which works with all, to get codes for DSi.
You can play Nintendo DS and DSi games on the 3ds, but the 3ds doesn't have a slot on the bottom for Gameboy games.
yes
No, simply because the action replay was built for DS games. You can't play 3DS games on a DSi anyways because the software that the DSi runs won't read the newer chips. Also, the 3DS chips won't fit into a DSi because of the way that the 3DS chip was designed. However, the DS games can be played on a 3DS because the newer systems can recognize the older games, you just can't use the 3D feature.
Yes, any charger that fits a DSi can be used to charge a 3DS, 2DS or New 3DS, they all use the same charger.
Yes. The DSi and the 3DS use the same charge cable. As well, the DSi charge cable can be used to power the 3DS' charging cradle too.
No. A DSI cant use a 3DS charger.
You can import most DSiStore games onto a 3DS from the 3DS' memory management menu. You can also play Monster Finder, which is the only true 'DSi game'.
The 3DS uses the 'same Wi-fi', it support WPA and WEP encryption, which the DSi supported too, but the DS could only use WEP.
Yes, they use exactly the same charger, which is the same charger as the two DSi models also.