Use New Super Ultimate Injector for Nintendo 3DS?
If you want your injected game labels to look "authentic"...
First, here's the font the 3DS uses: SCE-PS3 Rodin LATIN BOLD. I use Size 14 for most labels, unless they fill the label too much, then I instead use Size 13.
Second, put the game's title and release date in the first banner text window, leaving the second one blank, and make sure to remove any errant whitespace in front of words.