Yeah, I studied Aikido briefly in college and found it quite powerful when a petite 65yr old Japanese lady could inflict the most excruciating drop-to-your-knees pain I've ever felt with barely a touch. But it takes a decade or more of diligent practice to achieve that kind of skill, and I found Judo, BJJ, and Krav Maga quicker to become effective with.
Freestyle Olympic wrestling also has many useful techniques for winning a real street fight, and as an activity it builds the type of strength that is very effective in a fight. Worth taking a look at wrestler and BJJ practitioner Daniel Cormier's recent win of the UFC light heavyweight championship over Anthony Johnson, an extremely talented striker, to see why this is the case. Johnson essentially had a small window of time to knock Cormier out, and he nearly did, but once Cormier manage to get a hold of him the fight was brutal after that.
Strength training and general athleticism alone too will often allow you to win over someone who practices a martial art that is purely focused on striking, especially one of the more ornamental ones. Hard to win against someone that can just pick you up and slam you on the concrete ala Quinton Jackson.
