Did you get all 255 stats, then?

I tried doing that, and managed to raise my stats enough to defeat Dark Valefor and Dark Ifrit, as well as all the monster arena creations except the last one (simply because I didn't capture the required monsters).

I gave up after that though, because to go any further meant getting ribbon on my armor, and raising my other stats to near max.... And raising luck was proving to be way too big a pain, especially when both earth eater and greater sphere were giving me dark matters more often than fortune and luck spheres.