Many people can struggle to deal with an opponent's dash dance. Remember that dash dancing is often used to bait an opponent into doing something unsafe while keeping the ability to dash away and quickly punish. If your opponent dash dances a lot, keep track of their dash dance distances. Some moves are better than others at hitting dash dances with longer strides. Many dash attacks can serve this purpose well. But always remember that when you commit to an attack, you are committing and losing your options. A safer option to deal with dash dancing requires some knowledge of hitboxes. If your character has a move with a lot of range and can more reliably poke a dash dancing opponent, try to threaten them with said move. Examples could be, samus F-tilt (fast and good range), Marth d/f-tilt (disjointed, good range), and so on. But don't always just rush in with the move. Your opponent can react to it if you're predictable. Always threaten with the move by positioning yourself before committing.