Mismagius is a powerful Pokémon, and was able to knock out two of Ben's Pokemon. She was used initially second and took out Ben's Ninjask quickly with her Shock Wave. She was then used again after Ben's Magmar quickly took out Izzy's Venonat, decreasing both of their number of Pokémon to two.
Mismagius battled Magmar despite having somewhat of a type disadvantage. She used Psychic to try and slow down Magmar but Magmar used Fire Punch, deflecting the attack. Magmar then continuously used Fire Punch to try and attack Mismagius but she activated her Levitate ability, giving her the chance to disappear in and out of the battle. After successfully tiring out Magmar, she was instructed to create a sound wave in order to falsely mask where she was levitating in the Smog. Magmar naively followed the sound, crashing into the stadium wall. Mismagius then used directly threw Water Pulse at Magmar, defeating him.
Mismagius was used again against Ben's last his Pokémon, Rhyperior. Due to Rhyperior at first not listening to Ben, Mismagius easily attacking the monstrous Pokémon with two Water Pulse moves. Rhyperior then hit her with a Hammer Arm without the help of his trainer, further causing dissension between the two. Mismagius attacked again with a water Pulse, but this time, Rhyperior actually followed Ben's actions, causing him to attack with a powerful Poison Jab, defeating Mismagius.