If we bought my DD2 a second hand DS can she share games? / games ideas for 5 year old

[sleepwouldbenice]

Feel rather embarressed to ask but this shows the extent of my gaming knowledge

DD1 has a DS - she plays on it occasionally - has tinkerbell, mario karts, nintendogs, cooking mama, animal something game, maths games

DD2 is 5 shortly and wants a DS. I know you can buy DS lites and DSIs etc etc from earlier thread but tbh happy buying her a 2nd hand DS to use for a while (and upgrade when she's older if need be) so questions are more about being able to "share" games

For something like mario karts when they both play and against each other - do you need 2 versions of the game (one in each DS) or do they connect with each other so you only need one copy of the game? same with maths games or anything else you complete with? Or do you need say a DSi for this?

Any games not work on the basic / classic DS? any ideas for a different game to the ones suggested for a 5 year old - her sister will probably share hers so may as well get something new

Many thanks

DS, DSlite, DSXL are all the same just different cases, DSi is almost the same it has the addition of a media card slot and wi-fi connectivity so you can download games from Nintendo website, it all so has a camera which at least one game used, mean that game was only ever any use for DSi.

DS games save data to the cartridge, so if they both want to play the same game they may need two, most games have 3 save slots in but some only have 1 so the other kid may save game data over the first kids.

2 player games very, you will have to read the instructions that come with the game, most you will need two cartridges but others can transmit a race track etc over to the memory of the other DS so only 1 cartridge is needed Mario Kart can do this but due to the memory constraints you don't have any option to choose who you play as etc and your tracks are limited.