I think the only pokemon that can get Volt Tackle is Pikachu,catch a Pikachu that hold a light ball,theres very little chance that a Pikachu can hold a light ball,most of the time,it hold a oran berry.This is how I did it,it was in Pokemon Pearl,but I think it goes the same.I went in the trophy garden at the grassy area,I use a honey,and it lure out a female Pikachu, I caught it ,and it was holding a light ball,then I breed the Pikachu thats holding a light ball with a male Pikachu in the daycare, and got a pichu egg,when it hatch, it knows Volt Tackle and it has a Pokerus.