Here's a video for reference on the abilities and moves for Clark and Leona in King Of Fighters 13. I have to say Clark is pretty awesome in this game. Which is kinda crazy since they actually removed some of his useful moves like the shining wizard (against people who turtle too much) and still he's effective.

As for Leona well, she was always pretty good but her EX jumping SDM (I forgot the name of it) which was kinda tricky to pull of to me looks like it was made for effective, also it has a neat effect graphically she goes into Orochi Leona mode for a second.

Anyway here's the video.