I agree with @Kittyline Volo is too easy I watched a yt video about him as a super hard boss IT SAID HE WAS A NIGHTMARE TO FACE, BUT MY WEAK TEAM (no offense to you guys) SQUASHED HIM I ONLY USED LIKE FIVE POKEMON FOR THE FIGHT, ONLY TWO OF THEM HAVING STAR ROLES
My team to fight him was Level 87 Decidueye Level 76 Fridge rotom Level 81 Dialga Level 88 Garchomp Level 76 Sneasler Level 74 Manaphy Here's how the battle went Volo sent in Spiritomb so I switched Decidueye out with Manaphy who moonblasted it and almost defeated it. Volo healed it. I used the move in strong style and took it out. Roserade attacked and Manaphy did good damage before fainting because of JAGGED SPLINTERS. Sneasler took out Roserade with Dire claw, and Volo sent out Togekiss, who got paralyzed and almost fainted to dire claw. He sent out Garchomp and fainted Sneasler. I sent out rotom who one-shotted Garchomp and so did Arcanine. My Garchomp returned the favor and Volo sent out Togekiss (It was paralyzed for a bit which helped). I revived my pokemon before I used agile style double edge, and he sent out Giratina. And here's the most ridiculous part. Decidueye kept tanking hits, hitting back, and healing itself with roost. (Yes my Decidueye still has roost on it's moves, It also has Magical leaf, which really saves me.) Now somehow Decidueye took out Giratina and got origin form to a quarter of it's health. The Manaphy hit it with the final moonblast and I won. Honestly Volo isn't as hard as he seems and a weak team like mine was able to do better than legendaries, so in the end don't stress about the Volo fight. Buy a few Max revives get your team for the battle and try with some sneaky strategy.