You know, I never even really thought about the possibility of Kong debuting on Smackdown, but it makes just as much sense as her popping up on Raw. I mean, yeah, the Diva's Champion is on Raw but if I'm not mistaken, the champ is allowed to appear on both brands.
Honestly, it doesn't really matter. I have a feeling that she's going to be introduced by Cole since he's clearly setting up for some kind of confrontation with the Divas as evident by his constant(yet correctly spoken) criticisms of the entire division, most notably during Eve's matches. I could see maybe Eve coming to Smackdown to defend against someone like Layla and then while Cole is talking shit and Eve is trying to get at him in the Cole Mine, Kong comes out and destroys her. Just as effective as any other way of debuting her.
So yeah, it could just as easily take place on Smackdown.