You'll have to make a new account and basically ignore all of the progress you've made, and the end value of it is pretty worthless in practice. But if you really, really want to start your adventures with a Pikachu, here's how you do it.
When you create a new Pokemon GO account, you're given the option to pick one of the three original starters from Pokemon Red or Blue: Bulbasaur, Charmander, or Squirtle.
But there's a fourth option: everyone's favourite electric mouse, and the starter from Pokemon Yellow, Pikachu.
Catching Pikachu at the start is the same as picking any of the other Pokemon. The trick is to walk around and ignore the other three starters until the cheeky mouse appears on the map.
But as everyone else has discovered -- and as we pointed out in our guide -- it doesn't really matter what starter Pokemon you pick.
Pokemon GO works through the mass collection of Pokemon, so unless your suburb is infested with electric mice you won't be holding gyms with a Pikachu any time soon. It also means you're more dependent on evolutions to grow a Pokemon's power, which is a bit disappointing for those who liked the cuter, pre-evolution versions of their little friends.