For this metagame, Megas get a massive nerf. Their exclusive abilities are no longer exclusive, and they have a lot of competition from non-megas, especially their premega form, who can have two abilities. However, some are still good.
Alljokesaside I hope you are happy.
Pokemon: Mega Altaria
Why its still good: Altaria-Mega has a unique dragon fairy typing, giving it a solid niche. It also has great stast, a boosting move, and the ability to go special, physical, or mixed. While its no longer one of 3 Pixilaters, it has the advantage of 100 base stats to go with that boost. It also has reliable recovery, team support such as heal bell, and a nice premega ability
What gives it competition: Fairy types in general can now all run ate, making any one of them a theoretical replacement. None are as good, but they don't take your mega slot.
Pokemon: Mega Metagross
Why its still good: it has a great speed tier, the great steel type, good bulk, great attack, coverage, and a nice premega ability. Tough claws is one of the best abilities you can get when going mega, and it buts that to good use.
What gives it competition: Jirachi, Jirachi, and more Jirachi. Jirachi has a similar speed, the amazing serene grace, similar bulk, healing wish, and the ability to bluff other sets. It also has better coverage, albeit at the cost of a lot of power behind its attacks.
Pokemon: Mega Medicham
Why it's still good: nothing else has pure power (other than the slow regular form), and it puts it to good use. Simply put, it's attacks hit like a truck.
What gives it competition: just about any physical attacker with coverage. Medicham is walled by Mega Sableye and psychic types like Cresselia, which is super annoying.
Pokemon: Mega Alakazam
Why it's still good: it has a great special attack, trace is far less likely to get a junk ability, and it has an amazing speed tier. With the new almost complete lack of scarfs, it's often the fastest thing around
What gives it competition: half a dozen ou special attackers, like regular Alakazam, Latios, and azelf thanks to their own good speed and greater power.
Pokemon: Mega Pinsir
Why it's still good: nothing else gets aerilate thanks to it being banned. It has a good speed tier, coverage, and boosting. It also has a neat stab priority, just like standard, and has an intimidate resistance or mold breaker premega.
What gives it competition: the wide variety of ages, plus talonflame. Powerful Non-normal priority is no longer rare, and can be slapped on nearly any attacker with quick attack or extreme speed. Talonflame also has a wide variety of choices, and can be better at any given role. Of course, it can't do all of that at once.
Pokemon: Charizard-Mega-X
Why it's still good: it hits like a truck, has good coverage, boosting options, and it has few to no counters. It also carries the possibility to run bulky sets and surprise the few it has.
What gives it competition: any dragon type, like Salamance and dragonite, who have similar bsts and can run a second ability. Many other physical attackers do the same, like talonflame.
Pokemon: Charizard-Mega-Y
Why it's still good: It nukes things in the sun with 159 spa. It's still got good speed, and most of its counters are badly crippled/not helped (Chansey, Heatran).
What gives it competition: any fire type can now run desolate land or drought, making it less unique. Regular charizard, for instance, shares its typing and has solar power.
Pokemon: Mega Lopunny
Why it's still good: it has an amazing speed tier and perfect coverage, a fact which is unrivaled in the metagame. Additionally, it has fake out to safely Maevo and stop sweeps.
What gives it competition: scrappy meloetta-p. While it requires a turn each time it comes in and doesn't have fake out to do so, it has a far greater bulk on that turn. While it's slower, it has better bulk in both formes and knock off, as well as close combat over high jump kick
Pokemon: Mega Diancie
Why it's still good: it has a nice typing, great ability, and neat speed. Despite its lacking coverage, it has what it needs in terms of moves.
What gives it competition: The godlike clefable shares a typing and can have two excellent abilities- its natural ones and its item of choice. Sylveon hits harder as a fairy, and Terrakion is a better offensive rock type.
Pokemon: Mega Sableye
Why it's still good: prankster premega is a godsend, and magic bounce is huge for stall. It also still has its great movepool and good stat distribution.
What gives it competition: all stall magic bounce; nonmega Sableye. It no longer has as big of a niche, and regular Sableye makes up for its lower defenses by keeping prankster.
Outclassed* Megas
Pokemon: Mega Manectric
Is outclassed by: Raikou
Pokemon: Mega Slowbro
Is outclassed by: Reg Slowbro or Slowking
Pokemon: Mega Latias
Is outclassed by: Latios, Latias
Pokemon: Mega Gardevoir
Is outclassed by: Fairies in general, Sylveon
Pokemon: Mega Venusaur
Is outclassed by: Amoongus
Pokemon: Mega Aerodactyl
Is outclassed by: regular Aerodactyl, assorted rock types
*not completely, just mostly
