[FSLAR]

Scarf seems to be the one thing Thundurus-T has over its regular form but it actually isn't. Scarf Thundurs-T hits harder but doesn't outspeed threats such as Chlorophyll Modest Venusaur, Adamant Excadrill, and anything else similar. It's really a hard decision; the firepower or ability to outspeed neutral speed weather abusers. Agility is definitely the one set Thundurus-T does better. I think the Nasty Plot set will run a bit differently, more so wall breaking than sweeping.
Volt Absorb Raikou is a good offensive check as well, since it can outspeed with HP Ice and Thundurus can only use Focus Blast as its best move. However, Raikou can't switch in freely because it takes heavy damage from Focus Blast, and Superpower. It's kind of hard to say where Thundurus-T is overall. It's not the hardest thing to deal with, but you can't really switch in freely.