My TerraCott Subway team

[Vandslaux]

Whimsicott @Focus Sash
Impish (found it first, so don't ask me to change it to Bold, it has, like, what, a 1 HP dif. from an Impish Beat Up?)
Prankster
252 HP/252 Def/4 Speed (or 4 Sp. Def if he can still outspeed Terrakion without it)
Stun Spore
Tailwind
Helping Hand
Beat Up

I really don't know what to do about the EVs. Defensive seems stupid to me when I have a Sash. Beat Up Terrakion for 4 Attack raises and paralyzes stuff, and after the Beat Up, powers up with Helping Hand.

Terrakion @Life Orb
Adamant
Justified
252 Atk/HP 4 Def (max Speed is kinda unnecessary because of Tailwind, and it forces me to run a ton of Speed on Whimsicott)
Helping Hand (I just caught it, so yeah, I don't really have anything to replace it with)
Rock Slide
Protect
Sacred Sword

The star sweeper. He absolutely rips stuff apart. I've OHKOed stuff like Krookodile and Flygon that resists Rock Slide with a +4 LO Helping Hand-boosted Rock Slide.

The cleanup crew:

Typhlosion @Fire Gem
Modest
Blaze
My SS ingame Typhlosion, so I don't know the EVs
Eruption
Heat Wave
Focus Blast (I don't care to breed on my SS for HP Fighting, and I don't use it THAT often)
Bulldoze (filler)

One of my cleaners. Eruption + Fire Gem + hitting both opponents = win. Heat Wave for when my HP gets low, Focus Blast for things like Houndoom, and Bulldoze is mainly filler, but it can be handy if Tailwind runs out.

Latios @Choice Specs
Timid
Levitate
4 HP/252 Sp. Atk/252 Speed
Draco Meteor
Thunderbolt
Psyshock
Surf (I only use this if I'm partnered with Whimsicott, obviously)

My other cleaner. Specs Draco Meteor still hits hard after the Sp. Atk drop. T-bolt for Waters, Psyshock for Fighters, and Surf for if I need to hit both opponents.

Considering replacing Typhlosion with a Water Gem Wailord. So, is this team any good?

 

[Larry]

The Terrakion I use has
-Rock Slide
-EQ
-Close Combat
-Protect

After looking at your EV's I kinda wish I didn't go with max speed EVs...

 

[Vandslaux]

Yeah, Whimsicott needs to be faster than Terrakion so he can Beat Up before Terrakion attacks. I'm actually at 12, and I haven't EVed Whimsicott and Terrakion. I really should EV Terrakion, at least.

 

[Larry]

Yeah, Whimsicott needs to be faster than Terrakion so he can Beat Up before Terrakion attacks. I'm actually at 12, and I haven't EVed Whimsicott and Terrakion. I really should EV Terrakion, at least.

Yeah my Whimsicott is Timid with max speed which let's it outspeed my adamant Terrakion with 252 speed EVs.

 

[Vandslaux]

Now that I think about it, I should just go with max Speed on both of them so I have Speed outside of Tailwind. It's not like I have anything else to use Whimsicott's EVs for. And my Whimsicott is outspeeding Terrakion without Speed EVs anyway.

I guess I should just use some EV-reducing berries (after trading to my White) on Typhlosion and EV him 4 HP/252 Sp. Atk/252 Speed?

Yay, I was concerned if Typhlosion had bad IVs (I had also spent almost all my BP on my SS teaching him Heat Wave), he has Relatively Superior!

I'm also considering replacing Surf with Energy Ball. I HATE WATER/GROUNDS. They just so happen to resist all my main offensive moves (Rock Slide, Eruption, etc.)

 

[Larry]

Another thing I do differently is run Toxic on my Whimsicott rather then Thunder Wave...

 

[Vandslaux]

Bulky Grounds = bane of TerraCott.