For each stat, the formulas have this form:
stat = MAX(Y, B) + A
where
Y = the aeon´s stat value if you´d only raised Yuna´s stat
A = the aeon´s stat value if you´d raised it directly using the Aeon´s Soul
B = the aeon´s stat value if you´d only fought battles
MAX is a function that returns the largest valued argument
The MAX function is applied for each type of stat. For example, the aeon´s HP
is computed as if it were based only on the number of battles fought. Then the
aeon´s HP is computed as if it were based only on Yuna´s stats. The higher of
the two is taken to be the actual HP. The same process happens for each of the
other stats.
Section 3 shows how to calculate Y; Section 4 shows how to calculate B;
Section 5 shows how to calculate A.
Terence suggested the following auxilliary stat, which he called the Aeon Power
Base:
PBase = [yHP/100] + [yMP/10] + yStr + yDef + yMag + yMdf + yAgl + yEv + yAcc
When a stat name is preceded by ´y´, it´s refering to the value of Yuna´s stat.
[] represents the floor function, which basically rounds a decimal value down
to an integer.
Here´s the formula for an aeon´s stat based on Yuna´s stat:
stat = [yStat * x] + [PBase * y]
Each aeon has different values for x and y for each stat. See Section 3.1 for
a list of the x and y values. Note that the aeons´ stats have the same caps as
Yuna´s stats (255 for core stats, 99999 for HP, 9999 for MP). Let´s do some
examples.
First, using Yuna´s base stats, we´ll calculate Anima´s base stats.
PBase = [475/100] + [84/10] + 5 + 5 + 20 + 20 + 10 + 30 + 3 = 105
HP = [475 * 120/100] + [105 * 8] = 1410
MP = [84 * 4/100] + [105 * 4/10] = 45
Str = [5 * 330/100] + [105 * 1/6] = 33
Def = [5 * 100/100] + [105 * 1/5] = 26
Mag = [20 * 70/100] + [105 * 1/12] = 22
Mdf = [20 * 100/100] + [105 * 1/30] = 23
Agl = [10 * 40/100] + [105 * 1/20] = 9
Luck = 17
Ev = [30 * 50/100] + [105 * 1/20] = 20
Acc = [3 * 200/100] + [105 * 1/20] = 11
Now let´s see what Anima´s stats are when Yuna is maxed.
PBase = [9999/100] + [999/10] + 255 + 255 + 255 + 255 + 255 + 255 + 255 = 1983
HP = [9999 * 120/100] + [1983 * 8] = 27862
MP = [999 * 4/100] + [1983 * 4/10] = 832
Str = [255 * 330/100] + [1983 * 1/6] = 255
Def = [255 * 100/100] + [1983 * 1/5] = 255
Mag = [255 * 70/100] + [1983 * 1/12] = 255
Mdf = [255 * 100/100] + [1983 * 1/30] = 255
Agl = [255 * 40/100] + [1983 * 1/20] = 201
Luck = 255
Ev = [255 * 50/100] + [1983 * 1/20] = 255
Acc = [255 * 200/100] + [1983 * 1/20] = 255