Based on my rather meager experience against one Pikachu player who I can beat (As sad as it is, I've never played against K Prime despite living in the same city): It's around even like everyone is saying.
When he started spamming T.Jolt, I just slowly walked forward and shielded the whole time. He his last T.Jolt was close enough, I'd jab, clank with it, and then jab again and hit him. Once Ike is starting to close the distance, quit the spam.
He liked to use Fair against my shield once I got in close enough, land and go right into Dsmash. Seemed to work well against me, but my reaction time is terrible. Don't know how other Ikes would handle it. *shrugs*
When using QA to get back on stage, you might want to be careful if the Ike is charging Eruption. Timed (predicted really) right, and it can hit you before you can grab the ledge, and the SAFs can mess you up if it's just the wrong stage, and you tried to land right behind him for some odd reason.
I also know most Pikachu's don't do this but: don't use Skull Bash to recover and land accidently onstage. It's Counter Food. :D
Thunder when I'm trying to recover is a serious pain. Most likely, its going to hit me, the only question is if it will hit during Aether's SAFs or not. T.Jolt spamming also works for free damage, but probably won't gimp Ike.
Try to not go against Ike in the air. Sword beats rat.
Dsmash is fairly good against Ike near the stage edge. Even if Ike DI's out of it, there is the chance I'll end up DIing off stage. Don't rely on it, but it's there.