If all you want to do is play DS games, the only other thing you'll need is the SCDS1 loader (the software that runs on the cart; you don't need any special software for the computer). You can get tha latest loader from the GBAtemp download center or the Supercard website.

 

If you want to play GBA games you will need a slot 2 (GBA slot) flashcart of some sort. There are quite a few choices, and they boil down to three major catagories:

• Old style GBA flashcarts. These use NOR flash memory (slow to write, as fast as ROM to read) and require special software to write games to the cart.
• Modern slot 2 flashcarts: These use memory cards or internal NAND flash memory (faster to write than NOR, but slower to read - the roms must be copied to RAM in the cart each time you run them) and have a FAT filesystem. You usually still need to use a patcher or game manager with these.
• GBA expansion carts: These carts only add the ability to run GBA software to a slot 1 cart; they cannot be used on their own. All files are stored on the slot 1 cart and transferred to the expansion as needed. You use them by running a loader from the slot 1 cart that backs up the save for the last game you ran, then copies the new game and its save to the expansion. They are the simplest to use because the current loaders do not require you to patch the GBA roms, you just drop them on the memory card like DS roms.

If I were choosing one of these today I would go with a GBA expansion cart - either the EZ-Flash 3 in 1 or the eWin GBA expansion. Both are cheap (less than $20 for the eWin, $19-$25 for the 3 in 1), easy to use, and they do the job quite well.

If you need a cart with a clock so your pokeymen can know what time it is, your choices are much more limited. Very few of the carts available today have a clock.

Don't get a slot 2 Supercard, they really suck for GBA games.

 

Either the Supercard DS One or the CycloDS Evolution. I'd recommend the Evolution simply because of ease of use, but either should work quite well. Team Cyclops has been doing an excellent job of keeping the Evo updated and adding new features, and it is simple and easy to use. The only drawbacks are that it doesn't have a spring loaded microSD slot (some people consider this a plus), it doesn't automatically skip the health & safety screen and the DS menu (likewise), and it is just about the most expensive slot 1 flashcart available (except for the DS-X, but that doesn't count).

That said, I don't have an Evolution, and I'm going to be recieving an SCDS1 in the mail any day now. The spring loaded memory card slot and skipping the health & safety screen are important to me, and the SCDS1 has both. It also has most of the features the Evo has, and one more: It can display a game guide (grand talk for a text file) on the DS while the game is running. The Evo will probably get that feature before too long (it is planned for a future update), but it doesn't have it right now.

One big plus the Evo has over the SCDS1 is that it supports the 3 in 1 directly, so you can run GBA games from the Evo menu without having to start a loader first.