How would you have changed the concept of Mega Evolution in the games to make them easier to swallow? I feel like for a lot of Pokemon their Mega Evolutions practically replaced them in terms of usage and image, like Lucario for example, and this owes a lot to the fact that Mega Evolutions didn't require much in the games to activate. Usually you just send out your Pokemon and Mega Evolve them the first turn they are out (with only a few exceptions for the Pokemon that have abilities that benefit them when un-Mega'd). There's no downside to Mega Evolving them for the most part as they remain Mega Evolved for the entire battle and they require nothing, in terms of an in-battle sacrifice, to go Mega. Z-Moves sorta approached this this right way by having Z-moves be one time only use pocket nukes that sacrificed the item slot and could be at least partially blocked by Protect. I feel like if Mega Evolutions operated on some sort of timer they would have worked better tactically rather than simply being a button you could push to replace your Charizard with a stronger one for the rest of the battle. Like a 3 turn timer for Mega Evolutions would have been neat because it would have given people a choice to either go Mega first turn or keep the Mega in reserve, much like Z-moves.