Defender X

Defender X is a boss from Final Fantasy X who is encountered near the bridge between the Calm Lands and Mt. Gagazet. It is called into battle by two Guado Guards who block the path under Seymour's orders.

Defender X is a heavily armored mech construct, so starting off with Auron's Armor Break should be the first move. It can do lot of damage with normal attacks, but these can be avoided by using Wakka's Dark Attack. Blinding it is also an effective counter to Haymaker, which can potentially KO one character outright.

Once Defender X's HP drops past 10,000, it will cast Mighty Guard on itself, and then begin to use Slowga on the party. Its most dangerous attack is Blast Punch, which will halve one party member's HP. The damage can be reduced with Protect.

If Lulu has learned any Level-three spells she can be used to great effect, and the damage she can do will be improved if Auron wipes out Defender X's magic defense with Mental Break.

A Cheap way of defeating this monstrosity is to have Tidus cast Provoke on Defender X. When in this state it will only use Blast Punch on Tidus, and since the attack only halves the current HP, the worst that will happen is Tidus will be reduced to 1 HP.