Perhaps this is a gender stereotype but let’s call a spade a spade: there are a lot more guy gamers than girl ones. If you want your girl to pull up a wii fighting stick, try these tips from WikiHow:

1. Find out if your girlfriend has ever played video games before. She may not be a full-blown gamer, but maybe she played Mario games when she was younger. If you know her gaming history, you'll have a better chance of finding a game she'll enjoy now.
2. Remind your girlfriend that if you both play video games, you'll be able to spend even more quality time together. However, be aware that it will only count as quality time if she actually does enjoy it, so try not to force an argument on the first conversation about this topic.
3. Pick out a game she might like. If you're not 100% sure she'll enjoy it, you can rent it.
4. Try to choose a game or game system that isn't too confusing, and doesn't require short reaction time. Many non-gamers are intimidated by button combinations. If you've ever gotten frustrated to the point of throwing the controller in a game, don't start with that one.
5. If you can, get a game that is multi-player or, optimally, co-op.
6. Consider your girlfriend's personality when picking out a game. Some girls may prefer the brightly colored, all-ages games like Katamari Damacy, Bust A Move, Lego Star Wars, Sims, or just about any Mario game. But remember that your girlfriend is an individual who could just as well go for Halo, Resident Evil, or Grand Theft Auto. In general, girls go more for games that involve good characterization and dramatic plotlines; even a modicum of these factors can make a game a lot more appealing for a girl.
7. Be understanding and supportive. When she first starts out, tell her that it's easy, and that she will catch on. Make her feel like this is something that she can do. Let her win. Try not to show any signs of being annoyed that she can't pass the 1st water zone for the 76th time in a row. As she keeps playing, she will get better and may enjoy the game itself.