If a chord is at root position and it is a major scale and it is shifted to a degree that makes it a minor chord, is the chord major or minor? example: C, E, and G is a major chord with c as the tonic. When shifted to the supertonic, D, it becomes D, F, A. So is this chord a minor chord even though the tonic chord is major?
Yes it is a minor chord.
The type of scale does not matter nor does the type of chord you can build off the tonic. Only the notes used to make the chord matter. A major chord will always consist of a root, major 3rd, and perfect 5th and a minor chord will always consist of a root, minor 3rd, and perfect 5th.
Dom's answer is 100% correct, but I wanted to offer something else that is a little too much for just a comment; it has to do with some important musical terminology, especially between "scale"/"chord" and "tonic"/"root." (And I apologize if this is due to a language issue; as someone currently living in a foreign country, I certainly don't mean to make fun!)
Based on your first sentence, you know what a scale is. Within this scale, we can label specific scale degrees. C is scale-degree 1 in C major, E is scale-degree 3, and B is scale-degree 7. (The upper C returns to scale degree 1; in this case, there is no scale-degree 8.) Thus your question actually references changing scale degree, not chord degree. In other words, scale and chord do not mean the same thing! (Jazz musicians often confuse these due to how improvisation is taught.) Next:
"C, E, and G is a major chord with c as the tonic."
The first part is correct: C, E, and G make a major chord. However, the C here is the root of the chord, not necessarily the tonic. The tonic pitch will always be scale-degree 1 of the entire key, and the tonic chord will be the chord built on scale-degree 1. (Thus C is the tonic pitch in this particular example, so in some way your statement is correct; but I still felt like it needed clarification.)
I say all of this because I wonder if the distinction between tonic and root might clear it up. The key point:
You can be in a key where the tonic chord is major, but another chord built off of a different root does not have to be major.
As a quick reference, here's a little image showing the standard triad qualities in major and minor. Upper case is major, lower case is minor, and the little circle by the vii indicates it is diminished.
Now, it's possible you knew all of this and this is redundant...but I wanted to clarify it just in case!