Ok, at this point with my fairly mature magic algo (still under massive tweaking when I get a clue

) can explain Tellah do 9999 damage.
The Tellah-Golbez battle is pretty simple. You don't even really have to know Golbez's magic defense.
Meteo has a base spell damage of 800.
That version of Golbez is weak vs Holy and carries the Weak+ modifer.
Therefore, the formula is like this (under a worse case scenario):
800 (base spell power) * 4 (Weak+ modifier) - 254 (highest magic defense possible) = 2946 (spell power)
If you do some quick math, you only need a 4x spell power multiplier for 9999 damage. Tellah has 5x. 16 (Tellah's base Wisdom)/4 + 1 = 5
Unless you level Tellah past level 70 and/or he's equipping the Cursed Ring, there is under no normal circumstance where you would see less than 9999 damage.
Ok... onto analyzing how Fusoya+Golbez's Meteo suckage. I can only assume that Golbez's stats are mirroring Fusoya. It would only make sense given
what you see in their battle.
Let's assume for the sake of argument that Zemus has maximum magic defense.. let's calculate how much Wisdom you would need at minimum to hurt Zeromus at 9999.
9999/(800 (base spell power) -254 (highest magic defense possible)) = 18, but since truncation is done, 19 is required for 9999 consistancy.
That implies that a Wisdom of 72 is required for 9999 damage (72/4 +1 = 19).
Note that FuSoYa starts with a base Wisdom of 40, so no matter how much he levels up (with ideal stat gains), he will never be able to do 9999 damage consistantly.
In the ideal situation (target has 0 magic defense), the minimum Wisdom for 9999 damage consistantly is much less...
9999/(800 (base spell power)) = 12, but since truncation is done, 13 is required for 9999 consistancy.
So, you will need a Wisdom of 48 (48/4 + 1 = 13).
Anyways... I figured it out.