Here’s a few basic things you can do when you’re opponent is preventing you from securing the side control position.
These techniques are demonstrated on the Submission Master grappling dummy.
First, you can just abandon side-control and drop your knee in to get knee on stomach position.
Secondly, you can collapse your body weight sideways, which is often enough to get the position.
And finally, you can also bypass his defense by going to north south.