Re: rubberman?
Logias are therefore confined to elements or element-type stuff. Smoke, Ice, Light, Wind, Magma, Sand, earth, fire, water. But in this class there are several divisions. You can't really put fire and BB's gravity power in the same division. He says it himself, he's special.
Materials, from nature or man-made, are paramecia. Like metal, rubber, diamond.
So what distinguishes logia and paramecia is 1. logia should be a stronger power in itself. 2. Logias are in most cases unhurtable. 3. Logias are usually elements of nature. 4. Logias can controll they element in nature I guess. So Croc controls other sand than himself and Ace probably other fires. 5. Logias are more rearer than paramecias.
So Luffy is not logia, 1.cause it has been certainly stated by Oda or in the manga and it is a common knowledge. 2. He isn't an element(altough a material that exists in nature in some form). 3. he is in most cases hurtable. 4. he cant control other rubber in nature(the trees I mean

etc etc.