)
If you read a some of the gigantamax dex entries, some of them are.
Toxtricity's in particular mentions that it's poison and electricity production go into overdrive, causing it constant agony, driving it into a frenzy.
In a similar vein, Mega-evolution is supposed to be really painful. Garchomps limbs literally melt to form the new blades on it's arms, and Salamance's wings fusing into the large crescent moon is not only incredibly painful, but infuriating for it since Salamance takes such pride in the wings it worked so hard to evolve and earn, so the pain and defilement of it's wings drive it into a fury.
I'm sure the others are equally as bad, shout out to Mawile growing an extra mouth, that can't be pleasant.
Pokemon is not the happy go lucky world we all like to think it is.
it very often is "Happy-crappy" literally.