The sorting of evidence
*disclaimer: the following is not legal advice. If you need legal advice, please consult an attorney that is licensed to practice law in your state.*
Understanding how evidence is introduced and how it is viewed as valid or invalid in the courtroom is actually quite complicated and can differ depending on jurisdiction.
In general, self defense cases will often allow evidence that was know to the defendant at the time of incident. If you can articulate why an unarmed person was a deadly threat by observation (you witnessed a display of their strength or skill) or by prior knowledge (partner abuse in which the strength and skill level is known), them often that can be used in your defense. If you find out later that your attacker is a martial artist or is significantly stronger than normal, it will often be inadmissible, as you could not have factored it into your decision at the time of the incident.
The same applies to your decision making. If, after your incident, you take a class on pre assault indicators to learn what is a precursor to violence, you still did not have this information at the time. Likely not admissible in court.
So what can be admitted into evidence? Articulable, specific training you have received propr to your incident that has bearing on the case. If you took a scuba diving class it doesn't really pertain to your defensive claim. However if you took a lethal force class, a pre assault indicators class (or managing unknown contacts), or a force on force class, it may very well help you in court. It establishes the why of your defense.
The best part of being able to articulate your training is that your attorney then gets to educate the jury about all of the things that you knew at the time of attack (creating a jury of your PEERS). The information they recieve can help them understand your actions as well as bolster your image as a responsible person.
When you train, keep a record. Keep your notes. Keep all the information that you may someday like a jury to also know.