I've given this a shot before, but looking back my description was pretty awful, so I'm going to try this again with as much description as possible.

So as the title says, this is a children's book series. I read it what must have been 15-20 years ago, so if it was ever popular in any sense, that's probably when it would have been. The first couple books in the series are each about a child who discovers he or she has a power they were previously unaware of. I think there were 5 of them, but that might not actually be true.

There are three I can remember. One discovers she can breathe underwater. She discovers this while doing laps in a pool. Another can speak to animals. He realizes this when realizing he is hearing ants that are eating a giant chocolate bar he won as part of a contest. Another has supernatural abilities with regards to weaponry. He has immediate mastery over all weaponry.

Over the course of the first books, each about one child, they discover their abilities and by the end of these books find each other. Throughout this time they are hunted by these creatures that they believe to be aliens. In the climax of the series, it is discovered that they are the children of scientific experiments to give people abilities, which is why they have abilities. Further, their hunters are not aliens, they are actually from the future and are the next iteration of the experiment and are trying to kill off the kids for reasons I can't remember.

Hopefully if any of you read this series back in the day, this should be more than enough for you to figure it out. I'd be sooo appreciative, this has been an itch I've been trying to scratch for at least 5 years! Thanks!