I dont trust edited files if someone else has done them but if you do then here they are. Loco Roco Halloween and Moto GP. Alternatively download the originals from yourpsp and use this to edit.

How to edit:
Open the eboot.pbp file in the hex editor and search for 2.81 in moto gp or 2.82 in loco roco and simply change the value to 2.80 then save and it works.

If you download the others I do not think that firmware 2.80 has been hacked to the point they can "Brick" your PSP yet but tont hold me to this I edited my files myself mainly because the above ones were not available this morning.