You need Pokémon that are high enough in level to match Cynthia's level 75 to 77 team. Good combinations are a Fighting type that can damage ghosts and a Ground type that can counter the Levitate technique.Continue Reading
Cynthia can be battled at her house in Undella Town at any time during the spring but only during that season. The season can be changed manually by setting the DS's internal clock to January, May or September.
Your team should be in the mid- to high 70s at minimum to keep pace with Cynthia's Pokémon. The stats on her Pokémon are also higher than normal for their level, so the higher yours are, the better. Volcarona is the most useful overall Pokémon against Cynthia's team. A Volcarona of a high-enough level is capable of taking out her entire team by itself. Only one can be caught, however, and it's at Relic Castle.
Even if Volcarona isn't powerful enough to solo Cynthia's entire team, use it to defeat the Spiritomb she sends out first. The Eelektross that she sends out second is the only other Pokémon that requires special consideration. This is where you need the Ground type that can counter Levitate, such as an Excadrill that has Mold Breaker. The rest of her team has more standard weaknesses.