Restricting movement to one plane, but smoothly switching what plane that is

I feel like this has been answered before, but I can't find it anywhere.

I know how to restrict movement for a 2.5d platformer, but how can you make so that at certain points the plane of movement switches to a different angle, then switches back if you go backwards to that point.

I tried raycasting down from the player and setting the Y euler angles equal to whatever platform the raycast hit, but that isn't reliable because the player won't always switch at the right time, and won't line up properly with the platform. Another problem, is where the platforms overlap at the "switching point", the raycast will only detect one, preventing the player from going backwards properly.

So any ideas? The effect I am looking for was implemented quite well in Kirby 64.