Another character specific achievement. For this one, you'll have to play as Tsuchigumo (the guy with the big red hair and the mask and the four arms) in any mode except for training. This includes local versus against a second controller.
For this achievement, you simply have to press forward+Y and hold it until he automatically does the dash attack. You'll know you've successfully done this when he does a golden dash towards the opponent. Simply repeat this 100 times for the achievement to unlock. It's worth noting that the moves don't have to hit. That said, if you're doing this against a second controller you can simply leave them on a higher platform and keep doing the dash below them so you don't have to keep doing a rematch. After you do the 100th charge, you'll unlock this.