Epic mickey and Star wars battlefront collection for me. For epic mickey i would have just made a collection of all 3 epic mickey games and put it on every system and pc.
At this point since you have a fat ps2 and having issues you might be better off installing a hard drive inside of it and playing your ps2 and ps1 games on it with no more disc needed to play. For ps1 games you would use popstarter to play ps1 games and open ps2 loader for ps2 games.
The only reason i can think of is with dev mode it requires having a credit or debit card tied to the system/account since it treats buying dev mode as a subscription and not a 1 time purchase despite it being a 1 time purchase.