and to get volt tackle you need a female Pikachu holding the Light Orb (an item that doubles the attack and sp. attack of a Pikachu when held) and breed it with a compatible male. How do you get a Light Orb? any wild Pikachu has a 5% chance of holding a Light Orb. if the first Pokemon in your party has compound eyes ability, i.e.
Butterfree Venonat Yanma Nincada Joltik Galvantula Scatterbug Vivillon
then the odds go up to 50%