Apparently there seemed to be limits on the number of battles you could do against each opponent: (Or maybe it was a limit of the number of wins which will contribute to your score)

eg.

Ominous Stones
Wins: 31

WIN LIMIT!

(Sorry for the font colour- that is what it looks like on the page)

That is from someone's ToW stats page.

After looking at a few very impressive stats pages, I think I'll be getting a pretty low trophy. Ah well.... I hope it is a pretty trophy anyway.