The defense can use character evidence:
For the defendant, if it is based on the defendant's reputation or opinion (but not on conduct in specific instances) in contrast to the crime of which they were accused to prove that they acted according to their character on a specific occasion
For the victim, if it is based on the victim's reputation, opinion, or conduct in specific instances to prove that the victim acted according to their character on a specific occasion
Both defense and prosecution can use character evidence:
For witnesses (other than the defendant), if it is based on the witness' reputation, opinion, or conduct in specific instances to question the witness' honesty and credibility
Otherwise, evidence of a witness' traits or personality cannot be used to prove that they acted according to their character on a specific occasion