Ratchet & Clank: Tools of Destruction was never released on PSP. It's a PS3-exclusive (2007). The PSP entries are:
Downloading ISOs/ROMs you don't own is copyright infringement. PPSSPP/RPCS3 are legal emulators; the onus is on you to dump your own games.
Recommendation: Buy Tools of Destruction digitally on PS3 store ($19.99) or wait for a PS Plus Premium streaming window. For portable Ratchet, play Size Matters on PPSSPP (upscaled, widescreen patch available).