"Maybe so, but the pokemon there get stronger the higher level your team is. Its almost supernatural how it goes. If I was to go there, with my current team, I would face upwards of around lv 70 to lv90 pokemon. With each of your strongest mons, I would assume you would be pushing close to lv 100 pokemon with maxed out IV and EV's as well as all pretty devastating attacks and stats. Even your Mewtwo would struggle" Selina told him, laying out the exact details of the Isle.
"You're probably right," Shiranui admitted, "It took the efforts of two Pokémon to defeat Saisei back at the Viridian Gym. Even one-on-one there are ways to defeat them."