The definition of congratulation is the act of congratulating someone. The word needs an "s" when you are using it as an expression of good fortune or joy. An example is saying congratulations on your victory to someone.

In congratulation, I am extremely proud of this work.

The correct grammar is "Congratulations, graduates."

You have to go on their page then on their congratulation list, at the bottom, it says, "congratulation this player on their game!"

-Kатнячп•Fυııэя

The noun form of "congratulate" is "congratulation."