Jab is the fastest move in the game at frame 1. It is great for close-quarters combat as it will beat any other attack. However, it is laggy on shield, and does not combo or dp much damage.
Forward Tilt is great as a boxing option. It is frame 6, slightly disjointed, and covers space well. It can knockout opponents at very late percents with the tipper hitbox. Many moves combo into this finisher.
A great anti air tool, Up Tilt hits both sides at frame 3, and sends the opponent upward. It can send opponents very far and deals a lot of damage.
Down Tilt allows ZSS to combo with a grounded move on DI in. It is fast, and puts her close to thr ground. It can hit ledge, and combos until mid percents. Otherwise, it is not used much.