I love the concept but it was executed poorly. My main gripes are
>balance
Some megas are better than others. Not just in a "I recommend this one" way, but some megas are straight up broken and some are worthless. There needs to be a lot more work put into making each one useful while also avoiding making them rip the game a new one.
>lack of risk
Most megas have no downside to just using them turn one. There are a couple good examples like maybe holding off Manectric for an electric move/the right time to Intimidate or Speed Boost Sharpedo, but for the most part there's never really a situation where you don't want to use your mega - especially since most are straight upgrades of their base Pokemon.
>distribution
Extra powerful didn't really need a buff, and thus didn't need a mega. It's understandable that they'd want to give standout Pokemon megas to ensure merch sales and hype, but if that had to be the case then they should have made the mega sidegrades in utility like Garchomp.
>giving every mega its own stone
Stupid idea. Just causes item bloat and forces them to reintroduce each stone every generation, or at least that would be the case if they were bringing them back. This one should be easy to retcon but GameFreak is too stubborn to retcon things.
Despite their flaws, I wish they'd keep expanding on Megas instead of throwing them to the curbs - making slight adjustments to repair their problems instead of letting them go to waste. Sadly, throwing things out is GameFreak's way of handling things.
