"Yawindro" Start HP should be around 20K.
Appearance: Like Dark Yojimbo, but slightly less broad shoulders, no dog but a Tonberry with him, and sixteen ( !) different knives with him.
Attack: A quick slash with any of the knives for a nice 10K of damage (Don't forget, that aint too high considering Anima does 12K when you GET her). Each knife does a different status infliction, ranging from sleep to posion to curse to death.
S.Attack: Cross-Cleave. As if he was seymour himself, but this attack exceeds 30K sometimes and puts Petrification on the enemy for one turn.
Overdrive: Final Summon. Yawindro uses the final Summon, which in turn allows any other Aeon to be summoned. Sin can be summoned too, but it is Weak compared to what you battle. I'll move on to the Final Summon stats and so.

Final Summon. 99,999,999

Final Summon has every Ability, Every Special, Every Move, Every Stat, in the game. MP is maxes as well and everything does 99,999,999 damage. Just joking

Final Summon. 2,000

Appearance: Yu Yevon, but white.
Type: Holy.
No attack available.
No magic available.
No skills available.
Only available weapon is Master Summon, which Summons an Aeon in OD.
Note all stats are 255, INCLUDING Agility and Defence and such.
Once Aon dies, Reversts back to Final Summon and deals 1,999 on self. This allows a kill if you manage to hit.
If it dies, it will very simple revert back to our loveable Yawindro.

Temple: There is no temple. Once beating Nemesis, a very speical Sphere comes to you: Unbelievable Sphere. It allows a character to summon Yawindro.