Here's some good 3DS themes that I and some others found

Home About me My games 3ds themes Home

If you want to install these on your 3ds, you're going to need homebrew, after you have homebrew, go to anenome3ds which is included in the guide I linked to, and select the download by qr code option. All of the themes pictured are from ThemePlaza

Some themes I Like

Zelda OOT

QR Code

Kyogre and groudon

QR Code

Found by Cagey over at lurk-n-leech

This cool gate thing

QR Code

Found by Lee over at Vampirepda

Minimalist red and black

QR Code