Rydia should summonBahamut, or Palom and Porom should use Twin magic to whittle down their large HP quickly. Yang and Cecil should help with their physicals while Rosa or Porom heal. The Master Instructor's physicals are mediocre in strength, but the damage adds up due to their high numbers.
For an easy win, the party can use a Red Fang and have Rydia or Palom cast Fira. It will immediately end the battle.