No its not a glitch. Shiny pokemon dont inherently have better stats than regular, unless they're caught via a research reward. For example, the Shiny Celebi research a number of
I feel bad for the people in these comments. I have never once paid for the Catch Mastery Research, I only ever participate in the free events. I played for about 6hrs and got multiple shiny Kabuto and a shiny Archen. Literally the first Kabuto I clicked on for the day was shiny. Stop giving Niantic your money guys.