Well, RPGs (Pokemon included) is the genre you'll get the most out of with MeBoy. Pokemon plays VERY good on it
. I'd recommend Dragon Warrior 1 + 2, and 3, Lufia, and FF Adventure/Legend, Crystalis...
Action/adventure games are a little hard to play with a 5200, but you could try Super Mario, WarioLand and some of those racing games.
Oh, if you're finding text hard to read and don't mind playing the game sideways on your phone you could try changing the rotation settings to 1 or 3 (turns the screen 90/270 degrees) and enabling scale to fit. That way most text is readable, but you'll have to play with your right/left hand only