| My take on it? Sit down and try it out- she may surprise you.
I'm a wunderkind myself- I was reading college level stuff by 2nd grade- and early on, my Mom tired of games like Candyland, Chutes & Ladders, and Under the Big Umbrella.
So instead, she taught me Gin Rummy, Blackjack and other card games. She didn't take it easy on me either- she played to win. By the time I reached the aforementioned 2nd grade, we were pretty evenly matched. At the same time she was teaching me cards, my Dad was teaching me Chess. To date, he's the only person I've played that I have never beaten.
Why do I tell you this? Because the biggest danger with really smart kids is them getting bored and trying to alleviate their curiosity without adult supervision.
So again, take the time to teach her the game. She may not get it right off the bat, but if she's really a smart cookie, she'll be kicking your booty before you realize it.
The main trick I can see is that games like Pokemon have the same type of complexity that M:tG has- that of deck building. She may quickly master the playstyle, but may have continuing difficulty building competitive decks for quite a while. | 
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