Unless you know what you are doing, high amounts of HP or preparation are recommended.

In FFX, the game's internal system works so that having a 255 Luck Rating COMPLETELY replaces Accuracy and Evasion (which must be left at base stats, around the 35-45 area) in order to have every attack of yours hit, and every enemy attack that can miss, will not hit you.

However, Luck nodes are a long and cumbersome process at best (Greater Sphere/Earth Eater).