>>50781098They're not really weaker. Keep in mind that my original criteria factors in all current uses for megas (raids, farming, support, etc., except GBL, since that doesn't seem to be a staple in any leagues yet).
Mega Rayquaza, as of right now, is the highest dragon-type DPS. However, considering that Mega Garchomp is only one point lower in DPS but makes up for it with 100 more TDO, you would pretty much always want Mega Garchomp in anything that isn't a solo, especially considering the weaknesses and neutralized resistances flying-type brings to the table compared to ground-type (it'll take more damage from rock and electric, while only bringing with it resistances to bug, fighting and ground). These type resistances are, of course, conditional; if you plan on fighting more Palkia and Zygrade than Dialga and Zekrom, Mega Rayquaza would be more useful. It could also become more useful in the future, assuming Dragon Ascent is in the cards.
Also, while Mega Rayquaza can function as a flying-type counter, Mega Garchomp being a ground-type counter is much more useful overall, along with psychic, fairy, fighting and ghost being better as well. In addition, while flying is a nice type for type-farming (for either candy [XL] or bonus XP), there are much better megas for those purposes, mainly Mega Pidgeot, which covers two of the most common types in the whole game. Mega Pidgeot is also very similar in utility as a flying-type counter compared to Mega Rayquaza, so if you only needed a flying-type counter, it would arguably be a better long-term investment, since it's much more useful for farming candy and XP.
Mega Salamence is just a worse Mega Rayquaza, not just by DPS, but also because Aerilate isn't in Pokémon GO, so it's just an outclassed dragon-type mega counter. In addition, it could also be a thorn in your side that it may cost the third tier of mega energy (300 to start, 60 afterwards, etc.), just like Mega Rayquaza will.
