I was fighting a guy in Black City with lvl. 58 Mandibuzz. The opponent had a lvl. 40 Luxray, It used Bite on me, and I took NO DAMAGE. Why? This is seriously NOT a lie I saw it with my own eyes.
It probably took damage you just didn't notice because the madibuzz probably had a lot of health and it looked like it didn't take any damage because the one hp drop just took off the speck of the bar.Now if you were looking at the numbers and it didn't go down then it was a glitch.As long as it doesn't keep happening and your game doesn't mess up there is nothing to worry about.