I'm playing Pokemon HeartGold on my iPhone and I love it!

I installed Ignited via SideStore. No Jailbreaking necessary. Not computer tether. SideStore can renew the side loaded emulator every 7 days when on WiFi. The iPhone is perfect for DS emulation with a stylus.

(Ignited is a fork of Delta with more options, and SideStore is a fork of AltStore, with no computer tether needed)