Well, I DO know this, Spekkio is stronger than Lavos. Lavos is actually quite weak when compared to Spekkio. Also, seeing as how Nu are quite strong (they have to be, that can take you down to 1 hp with a HEADBUTT!) it would only make sense that the self proclaimed "Master of War" would have to take his final form as a Nu. Also, Nu transcend time and space, their species can be sited at any point in time, so in a place where time ceases to exist, because it has come to an end, why would it not be that a Nu is there? I think Spekkio is simply the last Nu, and that he has taken those other forms to guage others strengths, as he probably wanted to show his full power only to those he deemed as true heroes. That's about the only things I can think of on this topic... So I'm just gonna say, that's a tiny bit of food for thought.