In real-life English, all would be understood. How strictly "correct" they are could be argued. My answer is that third is correct, the second is correct for spoken but not written English, and the first is grammatically correct, but for unaccountable reasons the word "ain't" is considered to be "bad English."
The third looks odd in print, because of the repetition of the word "right." Because of the way a native speaker would intone the words, and because of a native listener's ability to process the grammar, it actually sounds OK and the listener might not even notice the strangeness.
The problem with #2 is that "aren't" is plural. We CAN say "we are," "are we not," and "aren't we." "I are" is just plain wrong, "are I not" is just plain wrong, and nobody woul every say them. Logically, "aren't" is a contraction of "are I not" so it logically ought to be wrong. But there is no "acceptable" contraction for "am I not."
One of the meanings of "ain't" is "am I not," so it is the right tool for the job, but, unfortunately, for mysterious reasons, "ain't" is stigmatized as "bad English."
The American Heritage dictionary's usage note for "ain't" says, in part:
"The stigmatization of 'ain't' leaves us with no happy alternative for use in first-person questions. The widely used aren't I?, though irregular, was found acceptable for use in speech by a majority of the Usage Panel as long ago as 1964, but in writing there is no acceptable substitute for the stilted 'am I not?'"
In real life, in speech, I would personally say "I am right, aren't I?"
Notice that in theory, "I am right, am I not?" and "Am I not right?" would be good answers, but in reality, as the dictionary says, they sound "stilted."