While going through the topic of Gimaira, the monster who had made appearance in Ultraman Taiga Episode 11 & 12, Taiga reveals to Titus and Fuma that he was the monster who Ultraman 80 struggled to fight. Ultraman Taiga tells them that he was a teacher on planet and also had taught him.
By taught, it doesn't mean that 80 had taught him Combat just like Leo or Zero. He taught him subjects like in every school. I think if you read the Ultraman comics that were published in the 80's, there are chances of seeing Ultraman 80 teaching the subjects to the Ultra students in the Ultra School (?).