Maximum stats for the Standard Sphere Grid:
99999 HP
999 MP
255 Strength
255 Defense
255 Magic
255 Magic Defense
250 Agility
230 Luck
60 Evasion
0 Accuracy

Maximum stats for the Expert Sphere Grid:
99999 HP
999 MP
255 Strength
255 Defense
255 Magic
255 Magic Defense
170 Agility
230 Luck
60 Evasion
0 Accuracy

Explanation of Luck:
To never miss, you need 75 more Luck than the target.
To never miss under Darkness status, you need 90 more Luck than the target.
To always get a critical hit, you need 100 more Luck than the target.

The enemy with the highest Luck is Dark Mindy, who has 130 Luck. That is why Luck maxes at 230.

Explanation of Agility:
The most important thing Agility does is reduce the amount of time between a character's turns. In this regard, Agility maxes out at 170. The other thing Agility does is increase the number of turns a character gets at the start of battle. In this regard, Agility maxes out at 250.

However, to truly maximize the number of turns at the start of battle, you need First Strike. Having First Strike and 170 Agility is the same as having First Strike and 250 Agility, which is better than having 250 Agility and no First Strike. But if you don't use First Strike, having 250 Agility is certainly better than having 170 Agility.

Note that the best way to use First Strike is to start the battle with characters who have First Strike and then switch them to characters who have the best weapons equipped. This way, you do not incur the penalty of changing the equipped weapons during battle. Auron doesn't have to switch because the Masamune is usually his best weapon.


Explanation of Evasion:
In order to always evade an enemy attack, a character's Evasion and Luck must add up to equal the sum of the enemy attack's accuracy constant and the enemy's Luck. The attack with the highest accuracy constant and Luck in the North American and Japanese versions is Malboro Menace's Mega Gastric Juice, which has an accuracy constant of 240 backed by 15 Luck, for a sum of 255. The attacks with the highest accuracy constants and Luck in the International and PAL versions are Dark Ixion's two attacks, which have accuracy constants of 254 backed by 36 Luck, for sums of 290.

That is why Evasion maxes at 122 in the North American and Japanese versions and 60 in the International and PAL versions. There are other combinations of Luck and Evasion that add up to the same amounts, but it is best to have the lowest possible Luck because it is far harder to increase Luck than Evasion.

As for 0MP cost it comes from an item called Three Stars, which you get 60 of for unlocking Earth Eater in the monster arena, you could craft weapons with the 1MP cost with 20 of those Three Stars but tbh its not really necessary.