There's no way to get a Pikachu with Volt Tackle. The move was introduced in gen 3 Sorry. :(
Have 2 Pikachu in the Daycare but 1 of the Pikachu holding a Light Ball and the Resulting Pichu will have Volt Tackle when it Hatches. One has to be Male and the other has to be Female.
Gen 7 Only
Go to Konikoni City in Akaka Island and talk to the Girl that has 3 Pikachu. Talk to her and She'll give you Pikachu's Z-Crystal the Pikanium Z. If you talk to the Girl again she'll ask you if she wants your Pikachu to learn Volt Tackle. NOTE: you have to have a Pikachu in your Party when you Talk to her.