Assault (the act of causing physical injury to another person) has 4 different classifications.
Assault 4 Defined
Assault 4 is the lowest classification and is an A Misdemeanor. This is an assault that occurs when a person intentionally, knowingly, or recklessly causes physical injury to another; or, with criminal negligence causes physical injury to another by means of a deadly weapon. Assault 4 usually is a misdemeanor, unless specific factors (such as a child witness being present).
Assault 3 Defined
The next level of assault is Assault 3. Assault 3 has a number of different possible factors, but the one that would be relevant in this scenario is a person commits the crime of assault 3 if the person, while being aided by another person actually present, intentionally, or knowingly causes physical injury to another. In this instance, if you were to assault, or punch, a person while being helped by another person, you could be charged with Assault 3, which is a C Felony.