Hi I was wondering if I would be able to install games to the SD card of my DSi with a flashcard so I can play it without needing the flashcard to be in my DSi. would this be possible?
The DSi/XL has about 256MB of internal storage, a portion of it is for the is reserved for the DSi/XL giving you less than that for free space. You would likely run out of space before you getting a DS game onto there (DS games can hit 512MB).
Short answer: NO.
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Getting a R4 clone and a microSD card to go with it can be had for less than 20 bucks.