Here's a link to play those PSP iso that requires 5.55 firmware or above for previous firmware. I've been a loyalty fans to m33 but their latest release was 5.00m33-x. I wouldn't dare to try out GEN release as everything would be reset to default setting upon installing and some people are actually having game play issue.
So until Dark-Alex release his next update, 6.00m-33 which I doubt would be any time soon, here's a quick way to patch those iso's that requires firmware 5.55 and above, such as Disgaea 2 on your m33 firmware!
Link : http://forums.qj.net/guides-psp-hacks-homebrew-emulators/159330-guide-how-patch-5-55-6-00-6-10-games-work-all-firmwares.html
So here's another link for those who want to patch the iso directly from their PSP without needing to access their PC. Obviously you will need to connect your PSP to your PC to copy the application, that's all.
Link : http://forums.qj.net/guides-psp-hacks-homebrew-emulators/163298-tut-easiest-way-patch-5-55-6-00-6-10-games-run-all-firmwares.html
I will post up the games that is compatible to 5.00m33-6 after decrypting by using those guides above in the near future:
I had tried it and it doesn't seems to work.
I do personally recommend you guys to download your ISO's from ESPALPSP instead of PSPISOZ. What I found is all ISO downloaded from ESPALPSP will always playable on my CFW 5.00m33.