Yes but Garchomp is the only mega evo that had a negative(that I've seen) hopefully that's false and the "popular" Pokemon all have a negative somewhere I mean mega Blaziken with increase attack with speed boost? dear god
There can be changes to moves/abilities. In BW for example, High Jump Kick went from 100 BP to 130 BP. D/P to Pt Hypnosis went from 70 acc to 60 acc. Sturdy buff from DPPt to BW. At the moment, I feel it's too early to say anything. But I can say that if Blaziken never got high jump kick or if high jump kick didn't go from 100 BP to 130 BP, Blaziken would never have been as broken.