How films could've done things differently #2

Yes I've got the name of the post wrong but ultimately no one gives a shit, My new rant about massive plot holes is Terminator Two: Judgement day  Which skynet sends an almost indestructible robot back to kill John Conner , Sarah Conner's son

                           Why didn't skynet send the robot back to the 1800's to kill Sarah Conner's great great great grandparents with their Superior technology and why give Sarah 10-13 years to prepare, training Conner and filling a massive bunker with weapons and there are many more plot-holes in this but I can't be arsed to tell you them all so here's something random

   That's right picachu was secretly working for skynet under squirtle,bulbasaur and charmander's nose....