Well, Nintendo did refer to Yoshi's Story as 2.5D. It had a little 3D interaction in that you could move along different paths that were either in front of or behind others. But other than that, yeah, 2D with 3D graphics. Wario Land or whatever the Wario game for Virtual Boy was could also be 2.5D, which actually has you going to the background at times (like Super Paper Mario).