Wow A1...
Anyway, for the actual discussion:
To my knowledge, our aerials tend to overpower yours (with the exception of our Nair and possibly Dair) and are more disjoincted, though yours seem to combo much better. However, we can WoP with ours.
Thundershock camping can be a ***** to get around, though our Bair gets through it, as does simple shielding. Most of the time, we shall approach with Bair to get through the spam however. I'm guessing by utilizing QAC you could probably take advantage of the slight ending lag on the move though.
On the ground, I'd say it's somewhat even, though to be honest, most of this matchup is spent in the air and on projectiles. Your Dsmash is a pain in the ***, despite being DI-able, and if we mess up our DIing, can set up for a thunder kill. Our grab game is good though, and you can expect low % grab combos and at higher percents Dthrow, sometimes followed up by aerials (I can't remember if your Dair beats our Uair, which would be the main factor in determining whether or not to follow up Dthrow.).
In general though, I think we tend to kill Pikachu earlier than he kills us, though it does depend on the situations. If thunder catches us in the air we are likely to die, especially since Kirby dies easier off the top, and of course, all your other KO options are good too.
Gimping Pika is very difficult (though it can be done). Outright killing him is usually easier. The problem is that while we have many killing options, most of them have to be mindgamed to work.
Thunder edgeguarding against Kirby can be effective, though I usually have enough jumps to get around it and occasionally punish.
Overall, this matchup seems pretty much even... until we get your power, at which point I'd put it slightly in Kirby's favor. With your power we can spam jolts a little more than 2x faster than you, and since we stay airborn during our spam, we effectively avoid your jolts, forcing you to approach. The problem is, this sort of 'super spam' also shuts down most of your approach methods, like QAC. Also, your ground options get severely limited, more or less forcing you to approach from the air, which is Kirby's domain.
TLDR version: Even matchup, but don't let Kirby get your power, as he will make your life hell with it.