George Washington the first president of the United States got 100 %votes.

He remains the only president to have received 100 percent of the electoral votes.
“So help me God” Washington said at the end of his oath.

And this expression became a tradition since that day and was added in the text of the oath, which all presidents read prior to undertaking their responsibilities.

What are the words that the RA Presidents declare when coming to the post?

The President of the Republic shall accept office in conformity with the procedure prescribed by law at the special sitting of the National Assembly by swearing the following oath to the people, “Assuming the office of the President of the Republic of Armenia I swear: to fulfill the requirements of the Constitution in an unreserved manner; to respect the fundamental human and civil rights and freedoms; to ensure the protection, independence, territorial integrity and security of the Republic to the glory of the Republic of Armenia and to the welfare of the people of the Republic of Armenia.”

Source: Iravaban.net