The easiest way to achieve matching number of points is to add duplicate points to all models that have less points than the others. Would that be acceptable? Why do you need exact match of number of points?
Do you need correspondence between mesh points (do you expect 123th point in mesh A to be at the same anatomical location as point 123th in mesh B)? If yes, then what you need is a spatial correspondence between meshes: transformation that transforms points of one mesh to the other. This transformation is computed by spatial registration algorithms. Once you have transform between mesh A to B, you can apply that to points of mesh A and get a mesh that has the same shape as mesh B, but contains exactly the same number of points and cells, in the same order, as mesh A.
There are several ways of registering meshes in Slicer. For example, you can import your meshes to Segmentation node and use the methods described in this post: align two segments to each other .