I love this! I want to see Kim Possible so badly, now: I never did, but I could still follow (and I have seen the sort of cartoons, I guess); I loved the evil genius! g
The part with Yugi and Yami at the very end was a bit... fanon, I think? I’m saying this because even though I liked it (because... heh. Serves Yami right!) and there’s a good reason for it here, it made me stop and think “okay, I have seen this before, and not in the original source”. (not trying to be rude or anything).
The scene in which Ryou and Bakura ‘discover’ each other is amazing: the whole romance is beautiful, never overdone, not even the main focus, and yet (and because of it) very touching and romantic.
I can’t believe you had it end like that though! Shego is evil – and funny: her interaction with both Ryou and Bakura was great!