I already stated it in another thread, but after using it in several playthrough teams I am a bit disappointed about Kilowattrel.
Now don't throw stones at me, I know it is a popular choice!
First, I want to say that it didn't perform bad in all of the playthroughs, in some of the playthroughs in which I had a strong team and did much exploring and catching, therefore had nice exp levels, it mostly did "okay" since it wasn't needed most the time and when it was needed, like for killing a water type it did what it was supposed to do. Like a standard electric-type.
But I also had a playthrough (which I didn't ended since I only wanted to test some pokémon and the used team felt not optimal overall) in which some of the flaws of Kilowattrel became apparent.
First, it is its defenses. While its typing is certainly great both in offense and in defense, its defensive stats are pretty bad, whch makes switching it in when a big hit is incoming pretty tough at times. Also, the Roost move is pretty much wasted on this pokémon since it isn't meant to be a tank.
Second, the movepool in general. While its available electric moves are generally good enough, the flying moves are not, in my opinion. Hurricane has bad accuracy and comes late, and the physical flying moves lean on its bad physical attack stat.
So overall, the only really useful moves are T-Bolt, Volt Switch and maybe Tail Wind.
And that's sad since it competes with several other good electric types.