Use the : Sonic Rush or Sonic Rush Adventure . These are official PSP-compatible (NDS games run on PPSSPP? No – wait, PPSSPP is for PSP, not NDS. Correction: Play Sonic Rivals or Sonic Rivals 2 on PPSSPP. They are excellent 2.5D Sonic games that capture the speed).
If you have found a specific modded ISO for PPSSPP, follow these steps to get it running: Sonic Mania Plus Ppsspp Android Download --BEST