Disgaea: Hour of Darkness

You need a high level person.

exactly what rivnen said, high level person, the god's only at lvl 100 so level up laharl to about lvl 300-500 (which can be done very easily in the Cave of Ordeals 3 map) and you can more or less solo the map

oh and another thing, its best to equip your characters w/ rank 38 weapons at least if they're at lvl 80 something, i personally beat prinny god at lvl 70 with a lot of lifting lol (and is it just me or did someone give me a -1 rating on my previous coment?!?!?! :O)

The way i did it i went to the cave of ordel and traind untill i was lvl 1021 then i went to prinny land. (make sure some caracters are also prity strong and you will do fine) also wile you have the cave of ordel try to get a warrior, brawler both male a theif a ninja and a scout all at lvl 200 and unlock majin if you have them then sorry about this but majins are the best way to difeat the prinny god hope this helps you :)

im a lv120+ Laharl-solo-er(that time). this is wad i do:

first of all, move Laharl to the back (9 prinnies there) and finish them with winged slayer. (u left 12 prinnies)
then, all prinnies except prinny god will come to u and use prinny dance (very waste-time atk), u'll recieve 4 prinny dance only. now except the 3 prinnies around u, others are in line form. use dimension slash. (u left 7 prinnies)
5 prinnies will surround u and use prinny dance. most of thier weakness is fire, now, blazing knuckle. (u left 3 prinnies)
ok this time prinny god will come to u too, and use prinny dance, too. the remaining prinnies will surround u and use prinny dance, too. anyway, fall back and use overlord's wrath to kill the 2 prinnies. (u left prinny god)
if u r low on hp, dispatch clerics or flonne to heal u.
final: use nightsever and go crazy on the prinny god

hope this helps u :)