When I saw this core, the first I thing I thought of was how bad Dugtrio is. However, I was going to submit something, and it had to include Dugtrio, so I went at thought about things it trapped. Heatran, primarily...but also Tyranitar. And, Tornadus-T thrives in the rain, which hates being disrupted by the sand that Tyranitar brings. So, I went about building a rain team. I knew I was going to have Tornadus-T and Dugtrio, so I quickly decided their sets. I know TFL ran Naughty Dugtrio with Rock Tomb, but I quickly realized that I actually wanted the Speed afforded by Jolly, which lets Raikou trap and kill mainly the likes of weakened Keldeo and Raikou, or at worst let it get off a Stealth Rock before dying vs the myriad of threats around that Speed range. The one small decision I made was to use Substitute > Stone Edge. The thing is, Dugtrio can't actually trap the targets of Stone Edge. Substitute does two main things; it lets Dugtrio deal with Chansey (it doesn't kill but it does a hell of a lot with max damage Reversal) even in the presence of Toxic, and lets it avoid Mawile and Bisharp Sucker Punches in case its Sash is broken by SR that I couldn't remove, or something.
I then naturally added Politoed, using a SDef build which gives me an Aegislash and Char Y check. My next concern was taking advantage of rain (Swift Swimmer) and getting SR off for Dugtrio, as well as Torn-T to some extent. I also realized that I wasn't going to have room to fit in, say, a Latias to Defog, because Dugtrio was taking up that extra teamslot. With all this taken into consideration, I decided to use Rapid Spin Kabutops, which gives me hazard removal and a ferocious rain abuser. My next pick was a Mega. I could have gone with Mega Scizor or Mega Mawile and then Kingdra or something, but Mega Manectric stood out because it gives a lot of momentum for the team combined with Tornadus-T's U-turn which especially helps Dugtrio get in and gives another bird check besides Kabutops, as well as another thing to outspeed Keldeo which is important because I don't really have a dedicated check for it. For the last slot I knew I wanted a Steel-type to pivot into the Latis and w/e. Aegislash was a natural pick at that point because I really wanted some offensive presence as opposed to using, say, Ferrothorn, and it's also the best Pokemon in the tier that provides a resilient check to a lot of things.
Overall this team is built around the Mega Manectric + Tornadus-T VoltTurn core which helps keep the momentum in my team's favor, which is important because of the nature of rain as a playstyle. I'm still not really sold on the usefulness/viability of Dugtrio, but I'll admit that it's definitely seem some decent use, particularly in providing easy SR. Anyways that's the team ^_^