The short answer is no. You cannot play Gameboy Advance games on your Nintendo DS with just the CycloDS.
The best slot-2 device to buy for the job is the EZ Flash 3-in-1, or the EZ Flash 3-in-1 Plus. Both devices look identical on the outside, but the plus is the more recent version of the two and had one or two bugs that have since been fixed. You can find out more about this here: Is the Evolution compatible with the EZ Flash 3-in-1?
The iPlayer is able to play GBA files (.gba) without the need for a slot 2 device, however it has been specifically designed to have a better in-built processor and RAM for that purpose, which means that the Evolution nor any other current flashcart is able to do the same.
NB: The iPlayer cannot play commercial Nintendo DS roms, it is designed for homebrew and video only.
The best solution is to buy both a CycloDS Evolution and an EZ Flash 3-in-1, and to use these two devices together with your rom dumps.
• Using your CycloDS Evolution for the first time
• Dump your DS/GBA games
• GBA Flashcart Compatibility
• Is the Evolution compatible with the EZ Flash 3-in-1?
• Need help understanding config.xml ?