As a Ground-type, Swampert was immune to Electric-type moves, so Wang Lu ordered Emolga to attack with a Flying-type move.
Both Pokémon were now constrained by their opponent's typing. Swampert could only attack with its same-type Water moves, while Emolga could only use its same-type Flying moves.
Both Pokémon were dual types, yet they had been forced to fight using moves of just one type.
Emolga's tiny body was exceptionally agile. Upon receiving Wang Lu's command, it rapidly absorbed Flying-type energy. With that energy empowering it, Emolga appeared behind Swampert in an instant, moving like an acrobat.
Once behind Swampert, Emolga unleashed the Flying-type energy within its body, slamming a torrent of energy into Swampert's back.
Because Emolga had no held item, Acrobatics gained a power boost. Combined with its same-type attack bonus, the strike took away a full third of Swampert's HP.
"Swampert, use Rock Slide!"
Once Emolga's assault ended, Zhang Cheng ordered Swampert to counterattack. He did not choose the Water-type moves Swampert excelled at, because Emolga was more vulnerable to Rock- and Ice-type moves.
Weighing the same-type attack bonus against type advantage, Zhang Cheng ultimately chose to forgo the bonus of a Water-type move and have Swampert use a Rock-type move that was super effective against Emolga.
"Gana~ Gana~"
Swampert was naturally less proficient with Rock-type moves than Water-type moves. However, Zhang Cheng regularly trained his Pokémon in all the moves they knew, so using Rock Slide was still easy for Swampert.
Under Swampert's control, dense Rock-type energy appeared above Emolga's head. Once the energy condensed, it swiftly transformed into a mass of broken rocks.
The rocks formed so suddenly that Emolga had no time to react before they smashed into its body.
The Rock-type move was highly effective against Emolga. After being struck by the barrage