The warp pipe , an ideal form of transportation. But to understand the complex mechanical components and such , one must know a great deal about quantum physics. So , I'm am going to take facts and stretch it and bend it until it reaches fiction to explain the Yoshi.

Yoshi-one must have the idea she is a dinosaur-is a small bipedal homeothermic creature with an amazing metabolic rate and stomach capacity , lives in the Mushroom Kingdom. Small berries with a normal maroon-type color , have the ability to somehow speed up the metabolic rate of the creature without killing the thing. Yoshi exists in a dinosaur world , so if evolution occurs naturally in nature , Yoshi could simply be an advanced form of a species of raptor. We don't even know if in the seven classes of biological classification wheather he/she could be classified by our standards. This creature must have an expanded mental capacity as well , for it can perform complex maneuvers with the tongue and may be able to speed up it's own metabolic rate. the genetic structures found in biological specimens are black and white in basic colors. Be we don't see many black and white yoshi , if any. So this would not be a logical explanation for yoshi come in a variety of colors. It is simple to say that the yoshi have genetic structures that determine their color-such as hair. But the genetic structures that form hair colors are not present because the Yoshi have no visible hair. Mutated genes may be responsible , also determining the way that their stomach acids react with the shells. How it contains the fireballs as it rushes up the esaphogaus is a mystery , but warping gravity may be responsible for the sand cloud that forms around their feet when she/he eats a green shell , and the enzymes in the salavia my be able to react with the shell chemically , but this is only chemical , not subatomic , so one must assume that subatomic particles are emitted during the chemical reactions , some that are still a mystery in physics. If the Mushroom Kingdom were to be put in scientific definition it may be that the Mushroom Kingdom is not of normal origins , that it is an unstable fifth or sixth dimension that is just an added "component" to the dimensions already existing. So , theoratically , this universe could collapse into it's own unstable space-time continuum and now effect us. So , Yoshi could be able to react in another way with the fabric of this universe , unknown to man , and unseen by physicists. this may be a logical explanation for her/his powers. Whether they have a gender...we've never seen one up close.