pokemon-go
I found two related questions to this already: Can my starter Pokemon be shiny? and Can you start with Pikachu in Pokemon Go?
I wondered that it is not an even number and so I guessed everybody has a different CP with the starter Pokémon. And in the case it's always the 13, do Pikachu or a shiny starter have a higher or a lower CP?
After digging deeper it seems you can in fact start with pikachu in Pokémon Go.
Reddit post "You can get pikachu as your starter pokémon"
You need to walk away from the three starters in the beginning of the game, just like in the animé. After you walk away from them 4? Times, Pikachu will show up.
pop news article agreeing that walking away gets you pikachu
I'm not sure there's an answer to why, beyond "that's what the dice / random number generator chose", buy you can likely power them up to the same max CP (they just started at different initial values). I suspect it can make more sense to power up a Pokémon who starts out with a lower CP but better attacks, rather than spending stardust and candies powering up an already-higher CP instance of the same Pokémon who has lesser attacks.
Best Answer
My starter Pokemon had a CP of 10, a buddy of mine had his starter with a CP of 14, so it seems that it differs a bit, but not by much.