The first time the party fights Raijin, two Galbadian Soldiers fight alongside him. Raijin uses only physical attacks. He is easily debilitated by blinding him. The player should save their strength for the upcoming battle with Fujin, as there is no time to heal in-between.
In the second fight, Raijin uses a new attack called Raijin Special, far stronger than his regular attacks. When Raijin's health is halved, he'll use a Hi-Potion to heal himself. The player can still blind Raijin to make him less of a threat, but Raijin Special will never miss.
If a female character is present in the party, and Squall and Zell are KO'd, Raijin will declare "I don't hit girls, ya know?" and cease to attack until the males are revived. This doesn't apply if he is blinded. This even includes Edea, although it is not possible to have her in the party against Raijin in a normal playthrough.
Raijin loses his ability to use a Hi-Potion, but gains a new unnamed physical attack that inflicts slightly more damage than his regular attack. After a few turns, he will cast Aura on himself, which doubles his attack power. He only uses Raijin Special, his strongest attack, after he casts Aura on himself, but he can still use it after the Aura effect has worn off. Raijin Special can deal thousands of damage, so with a weaker party, Phoenix Downs or Life will be necessary. Raijin will still prioritize attacking male party members, though if there are only females alive, he will announce "I won't take it easy on ya!" and start attacking them.