How to change Character/Controller to jump up through, but also land on platforms?

How to change Character/Controller to jump up through, but also land on platforms? Think Smash Bros. I know I can use planes but they are additional polys and work to attach to each platform mesh. Is there a way I can just edit the character to say only collide with normals faces in a positive directions?

as long as your platform is not being rotated then the answer marked as correct in the below link should suffice: