"Kiddy Grade" is a strange title for a science fiction series about superheroes. It refers to the idea that there are varying grades of "super", and the two we follow are considered to be in the lowest, or kiddy, grade (interestingly, the phrase "kiddy grade" does not appear anywhere in the show).
We follow Eclair and Lumiere, troubleshooters for the Galactic Union of Trade and Tariffs (GOTT - analogous to the WTO). They look like children, but we slowly learn that they have been around for quite a while. Eclair is fast, strong, wields a lipstick lariat, and is recklessly cheerful. Lumiere has the ability to control computers at a distance, and is forever saying "a lady should be more elegant" in response to Eclair brashness.
Over the course of the series we meet other trouble-shooting pairs working for the GOTT, like Sinistre and Dextre, Tweedledee and Tweedledum, and Alv and Dvergr. Each has different powers.
I won't spoil it for you, but trust that there is an over-arching story which ties it all together. This is a series which rewards going back and watching again - I have just finished watching it for the third time (first time was in 2004), and enjoyed it even more.
I originally bought this series as it came out, disc by disc, and that was expensive. Buying it this way is much cheaper, and there's no waiting for the release of the next disc!