For those of you who watched Dragon Ball, this is why Chi-Chi barely fights anymore...

[ZPolk01]

As, revealed by Goku at the Beginning of Z (Kai), Chi-Chi thinks that since the world's at peace, there's no need to fight? As for the upcoming threats, it's unknown why she didn't realize she can't live a normal life if Goku and Gohan don't do something? She did hold Gohan back most of his life, but he is participating in the Universal Tournament. It's unknown why she doesn't occasionally fight, she might be able to give the Human Z-Fighters (Krillin/Tenshinhan/Yamcha/now Master Roshi) a challenge, but I know, not now, since they're all way stronger than her, I mean, according to Goten, Chi-Chi trained him, so that's the last time she trained Goten, cause by Super, she holds Goten back from participating in the F. Trunks Arc, and probably held hin back from the Universal Tournament too. So what do you think is up with Son Goku (one of the strongest men in the world)'s wife and his eldest son Gohan (who is participating in the Universal Tournament)'s mother?

[Ki Breaker]

There's no need for others to fight now that it's peace is what she might have meant ( didn't watch kai, can't confirm if she said this )
ChiChi dosen't fight for the sole reason she dosen't need to and is far outclassed by everyone else, no point in being a lousy meat shield..
Why do you think videl stopped fighting? Even Yamcha and Chiaotzu don't fight anymore, people realize when they can't help anymore and get sidelined

[mabalia]

If she kept training she could be at Kuririn's level, with Goku as a teacher she could only improve. But I can see her training a bit to keep her skills in shape, but nothing too serious.

I miss fighter Chichi but I know she isn't interested. And I think if she were a Z fighter it'd mess Goku, like he enters the battlefield to find a bloody Chichi nearly dieing in the floor... it was already harsh to find his 5 year old son with a broken neck on Namek, don't need to add his wife to the scene. Of one thing I'm sure, she wouldn't play in any fight, she'd be serious and direct to the point.

[floofychan333]

The series just doesn't need another human fighter. Guys like Kuririn, Tenshinhan, Muten Roshi, and Yamcha are literally superhumans but since they aren't Saiyajins they're not really important and are now background characters. Chi-Chi isn't a fighter because she is intended to be a(n) (extremely annoying) mother and wife and doesn't really like fighting much. She only fought in the 23rd tournament because Goku was there and I don't think she really intended to win it.

[Lord Beerus]

Chi Chi doesn't fight anymore for the simple reason that the heroes, villain and other characters of the main cast got too strong too quickly for her to contribute anything of substance.