Do Nintendo DS Lite Skins fit Nintendo DS?

It would depend on which accessory you are trying to use.

-A DS Lite stylus will fit in the DSi's stylus slot; The difference is the DSi's is only a little longer.

-The DS Lite charger will not work with the DSi. This should be obvious that the DSi's, likewise, will not work with the DS Lite.

-Personally, I wouldn't get a screen protector for my DSi that was made for the Lite, as you probably know the screens are somewhat larger as well.

-Last note, any accessories that need a Game Boy Advance slot, such as the Guitar Hero grip thing, will not work in the DSi, because Nintendo dropped the Game Boy Advance slot on the bottom of the DSi. This also means features like Pal Park, for Pokemon games, won't work unless done with a DS, or DS Lite.

the DSi and DS lite are different in size. How can their accessory fit each other?