Before cannon, siege engines were pretty ineffective against castle or city walls. The only siege engine which could throw projectiles with enough power to have a chance against walls was the trebuchet.

The largest trebuchets could probably throw 15 kg or even much heavier stones at about 150 mph.

See this video of a modern replica, based on patterns from Dover Castle:

https://www.youtube.com/watch?v=RN18I-RBVm4

The problem with the trebuchet was that the accuracy was not great, so it was difficult to sling stone after stone to impact at the same place on the wall to eventually create a breach. (Although it was perhaps sometimes done. Edward III built a great war engine called "War Wolf" (probably a trebuchet) which created a breach in the walls of Stirling Castle in Scotland.)

Siege cannon were more powerful and more accurate, they created breaches in castle walls by firing multiple shots (often from multiple cannon) aimed at the same place until the wall collapsed and a breach was created.

Trebuchets were more often used to hurl rocks and other projectiles over the walls to create damage in the castle or town behind the walls.

To create a breach in the walls, Medieval siege engineers would rely on mining, digging a tunnel under the walls, then burning the wood supports in the tunnel so it collapsed and brought down the foundation of the walls creating a breach.

Very large trebuchets could damage walls, and possibly create breaches, but generally, Medieval siege engines until the development of cannon were generally not powerful enough to reliably create breaches in castle walls.