Now I'm no expert at VGC-style battling, so I won't critique your whole team. However, I think there is one thing I can help you with. Tired of Togekiss, you say? If I may do so, I would suggest replacing her with Mega Altaria. (Don't freak out about the "two Megas" thing, I'll get to that.)
Cumulonimbus (Altaria)@ Altarianite
Ability: Cloud Nine > Pixilate
EVs: 252 HP / 196 SpA / 60 Spe
Modest Nature
- Hyper Voice
- Roost
- Protect
- Ice Beam
Overview
This is your new Togekiss. It has slightly less HP and Sp. Defence than 'Kiss, but it makes up for it in superior typing, physical bulk, and offensive presence. It makes a fantastic bulky support and can fire of STAB spread Hyper Voice. It gets a plethora of moves, both offensive coverage and support. This is just one of the many sets Mega Altaria can run, and the one I believe best supports your team.
Synergy
Mega Altaria has good synergy with the rest of your team. I assume you were keeping Togekiss on because it could switch freely into Ground attacks, which Ferro and Heatran suffer from. While in base form Altaria still has the Flying type, so it can act as a one-time safeguard from Earthquake and Drill Runs. Base Altaria has something else to offer: Cloud Nine. This allows you to stop Mega Charizard Y and Mega Swampert sweeps before they begin, and have a teammate KO.
Enough with base Altaria, let's get to the Mega. Here's a comparison of Mega Altaria and Togekiss's typing defensively:
Mega Altaria: 7 resistances, 4 weaknesses, 1 immunity (+1 for base Altaria)
Togekiss: 4 resistances (2 quad), 5 weaknesses, 2 immunities
As the comparisons show, Mega Altaria has superior defensive typing. Both Fairies, however, are weak to the common Bullet Punch and less-common-but-still-deadly Ice Shard. I will deal with this later, in the Pairings section. Not much more for Synergy, but Altaria does offer spread Fairy STAB and a coverage move, while 'Kiss is reliant on flinch hax.
Stats and Moveset
Cloud Nine weatherlocks Sun, Sand, Rain, and – to some extent – Hail teams. Pixilate lets you blast STAB Hyper Voice at the opposing team. EVs allow for maximum bulk while still giving Mega Altaria a threatening offensive presence. Modest is to crush more things with Hyper Voice.
Hyper Voice is your only STAB attack, and really the only one you need. Who wants a Dragon attack when you have a stronger Fairy STAB? Roost makes Mega Altaria even more annoying to face and provides an instant 50% of her health back. Protect is mandatory for dodging Bullet Punch, Icy Wind and Sylveon's Hyper Voice. Ice Bea mis one of the many coverage moves Mega Altaria gets. It is chose over Fire Blast to hit threats like Landorus, Togekiss, and Thundurus supereffectively. Additional coverage moves will be provided in the Tweaks and Changes.
Clacs
196+ SpA Altaria Ice Beam vs. 0 HP / 0 SpD Garchomp: 312-368 (87.3 - 103%) -- 18.8% chance to OHKO – Just a little prior damage or double-targeting/spread moves will take him out.
196+ SpA Altaria Ice Beam vs. 184 HP / 0 SpD Landorus-T: 328-388 (89.8 - 106.3%) -- 37.5% chance to OHKO – Once again, prior damage/double-targeting.
196+ SpA Altaria Ice Beam vs. 0 HP / 0 SpD Thundurus: 164-194 (54.8 - 64.8%) -- guaranteed 2HKO – Yup. If partnered with Lando's Rock Slide then it OHKOs.
196+ SpA Pixilate Altaria Hyper Voice vs. 252 HP / 4 SpD Tyranitar: 264-312 (65.3 - 77.2%) -- guaranteed 2HKO – Altaria outspeeds and 2HKOs T-Tar before he can 2HKO back.
196+ SpA Pixilate Altaria Hyper Voice vs. 196 HP / 0 SpD Mamoswine: 388-457 (184.7 - 217.6%) -- guaranteed OHKO – Assuming it's not a Sashed Mamo.
252 Atk Tough Claws Mega Metagross Bullet Punch vs. 252 HP / 0 Def Altaria: 206-246 (58.1 - 69.4%) -- guaranteed 2HKO – The will to survive is strong.
-1 252 Atk Tough Claws Mega Metagross Bullet Punch vs. 252 HP / 0 Def Altaria: 138-164 (38.9 - 46.3%) -- guaranteed 3HKO – Works even better with Lando.
252+ Atk Technician Scizor Bullet Punch vs. 252 HP / 0 Def Altaria: 236-278 (66.6 - 78.5%) -- guaranteed 2HKO – Same as Mege Metagross.
252+ Atk Life Orb Mamoswine Icicle Crash vs. 252 HP / 0 Def Altaria: 117-140 (33 - 39.5%) -- 99.8% chance to 3HKO – She eats Ice attacks for breakfast.
+2 252 SpA Thundurus Hidden Power Ice vs. 252 HP / 0 SpD Altaria: 246-290 (69.4 - 81.9%) -- guaranteed 2HKO – Bear in mind that Thundy will have been hit on the turn it sets up Nasty Plot, leaving it unable to KO.
Pairing
Mega Altaria appreciates three things: spread damage, something to take out Steel and Fairy Pokémon, and someone to help her stop the weather. I think some good partners would be:
+ 
Lando and Altaria provide excellent synergy. Landorus provides much-appreciated Intimidate support, turning Altaria's 2HKOs int 3HKOs. He can also take care of Steels via Superpower and U-Turn out for a more favourable partner. He also has access to Rock Slide, and the damage from that helps turn Mega Altaria's 2HKOs into OHKOs.
+
Heatran and Mega Altaria compliment each other nicely. Heatran nails pesky Ice- and Steel-types who trouble Altaria, and Altaria eliminates Fighting- and Ground- types that Heatran would rather avoid. As with Lando, 'Tran and Alt assist each other with their spread moves.
+
These next two pairs are for anti-weather. For these, Altaria should be switched into the opposing Weather setter so that Cloud Nine takes effect. This pair, Rotom and Altaria, are for dealing with Sand and Sun teams. Altaria's job is to eliminate the weather, and Rotom's job is to Hydro Pump/Thunderbolt opposing Mega Charizard Ys. Rotom is also responsible for taking out Hippowdon, who Altaria can't scratch. Either one can destroy Tyranitar.
+ 
The final pair I shall suggest, this is for anti-Rain. Altaria switches in to negate the weather, and Ferro uses Power Whip to KO any opposing Politoed and Swampert. It is best for Altaria to Protect on these turns to avoid Ice Punch or Ice Beam, respectively.
Having two Megas
Having to Mega Pokémon is actually acceptable and quite common in VGC, as you only take four of six Pokémon per battle. Therefore, having both Mega Gallade and Mega Altaria on a team is OK.
Tweaks and Changes
You can modify Mega Altaria in many ways. You could fully invest in Special Defence in order to survive more blows. You could do away with Ice Beam and add Tailwind or Heal Bell. Fire Blast is equal to, if not a better option than Ice Beam (I chose Ice beam because 'Tran and Lando pretty much have that covered). It helps Mega Altaria deal with bulky Steels without having to rely on Lando and Heatran.
Sorry for the extremely lengthy explanation of one Pokémon, but I do hope it helps.
