Alrighty, here we go. This is is a decently-built team, but it could use a few improvements.
Mega Charizard Y
Not much that needs changing here. One thing that does need tweaking is the EVs. Mega Zard is really quite frail, and shouldn't be performing the role of a tank. Change the EV spread to 252 SpA / 252 Spe / 4 Def. The rest of my suggestions are up to you. Consider replacing Fire Blast with Heat Wave for more accuracy at the cost of less damage. You might also want to try Focus Blast in the place of Air Slash for extra coverage.
Ferrothorn
Pretty standard, but once again, the EVs need adjustment. 252 in each defence looks good on paper, but in practice it is better to focus on one side of the spectrum and put the other EVs into HP (or Health, in your case). In that case, I would suggest leaning more towards Special Defense, with a spread like 252 SDef / 212 HP / 44 Def. This lets you have maximum Special bulk while also buffing your Defensive side a bit.
Metagross
If it's not Mega, Metagross has no place in OU. It is outpaced by nearly everything and outclassed in terms of power by several other offensive Steel types. It's typing also doesn't do it any favours. For these reasons, I would suggest replacing him with Scizor.
Scizor@ Life Orb
Ablity: Technician
EVs: 252 Atk / 252 HP / 4 SDef
Adamant Nature
- Bullet Punch
- Bug Bite
- Roost
- Swords Dance
This is the standard set for setup sweeper Scizor. He has plenty of resistances and only one weakness, which you can see coming from miles away and switch into one of your three Pokémon that resist it. Bullet Punch and Bug Bite are STAB and get boosted by Technican, which becomes even more deadly after Swords Dance. Roost is there to heal off Life Orb recoil.
Garchomp
Life Orb Garchomp catches many people off guard, since the standard set is Lum Berry. However, as he gains popularity, people will start preparing for LO Garchomp. With that in mind, I would suggest the Choice Scarf set. It allows you to outspeed almost everything, and even some other Scarfers. Other than that, only minor changes need to be made from here. Replace Brick Break with Fire Blast and change the EV spread to 252 Atk / 252 Spe / 4 SpA. This lets Garchomp go mixed to take out the likes of Ferrothorn and Bisharp with ease. Since you have a Choice Scarf, I would suggest not locking in to Dragon Claw until all of the Fairies on the opposing team are gone.
Tyranitar
I know you had Aerodactyl in the question, but you commented that you had changed it to Tyranitar. I don't know what build you gave it, so I'll offer y suggestin for what will suit your team best.
Tyranitar@ Choice Scarf
Ability: Sand Stream
EVs: 252 Atk / 4 SDef / 252 Spe
Adamant Nature
- Crunch
- Stone Edge
- Pursuit
- Low Kick
Tyranitar now forms a deadly dual-Scarfer core with Garchomp. The EVs and Nature speak for themselves. Crunch is primary STAB and hits the likes of Gengar and Gothitelle hard. Stone Edge is secondary STAB and is uses to check Talonflame and both Mega Charizards. Pursuit is your tertiary STAB, and is useful since T-Tar forces a lot of switches. Finally, Low Kick lets you deal hefty damage to opposing Tyranitar, whom you outspeed thanks to the Choice Scarf, as well as Bisharp, Ferrothorn, and Mamoswine.
Starmie
You already have plenty of speedy Pokémon, so Starmie should be changed to a bulky Rapid Spinner. Change her item to Leftovers. Replace Hydro Pump with Scald for the nifty Burn chance. Recover takes the place of Psychic. Ice Beam can eitehr stay, or be replaced with one of Thunderbolt or Psyshock. The EV spread should be modified to suit a bulky Spinner. Try 252 HP / 4 SDef / 252 Spe. This lets you get the jump on thge opponent when you act offensively, and tank hits when you act defensively.
So there you have it! I'm sorry if I made too many changes, but I did what I thought could help your team better. You can use all, some, or none of my suggestions. Good luck in your competitive battling future!
