Yes, via Adrenaline (PSP emulator on Vita). Copy the save folder to ux0:pspemu/PSP/SAVEDATA/ .
Unlike modern cloud-connected games, Monster Hunter Portable 3rd saves directly to a single file on your memory stick (or a virtual memory stick on emulators). This file is named typically ULJM05800Q00.bin or NPJH50043 depending on your game version. It is vulnerable to: monster hunter portable 3rd save data
Before diving into complex transfers, it is vital to understand what constitutes a save file for MHP3. Yes, via Adrenaline (PSP emulator on Vita)
But whether you are a veteran hunter with 500 hours logged or a newcomer using an English-patched ISO, one thing is certain: your is your most valuable asset. Losing it means losing hand-crafted armor sets, fully upgraded weapons, rare carves, and your coveted guild card. This file is named typically ULJM05800Q00
ms0:/PSP/SAVEDATA/ULJM05800/ (JP version) ms0:/PSP/SAVEDATA/ULUS10567/ (US/EU fan-translated, if patched)