SNES didn't have a 3D accellerator... some games (i.e. Star Fox, Yoshi's Island) had the Super FX chip in the cartridge, and that served as the 3D hardware. It was rather slow, put out non-textured polygons, and could show maybe 20-30 on the screen at once and maintain a good framerate?
Doom used textured polygons and the framerate suffereed... a lot.
GBA seems to have a 3D accellerator (they are coming out with a game that looks kinda like the SNES star fox, and they are coming out with Doom, Wolf3D, and some 3D racing games).