Yojimbo was a push over. I had Paine as a Dark Knight, Yuna as a Berserker, and Rikku as an Alchemist. I just had Paine use Darkness over and over, and Rikku mixed potion + high potion every other turn. At the start of the battle I put Yuna in Berserk mode, but once that wore off I just had her attack. The most damage Yojimbo did to me was maybe 200 from his doggy. He only did Zanmato once.

Paine was at the highest level, 35, Rikku and Yuna were at 34.