A list of Amazing Pokemon for T-room that can activate it.(In Pokedex order)
Slowbro: Good S.Attack, High Bulk, and great movepool
Exeggutor: Great S.Attack and decent Bulk
Slowking: Good S.Attack, High Bulk, and great movepool
Porygon-2: Good S.Attack and Amazing bulk, and great movepool
Gardevoir: Great S.Attack, good special Bulk, and good movepool(Note: you should give Her the Iron ball if you are going to use her for T-room)
Claydol: High Bulk and good movepool
Dusclops: Amazing Bulk
Bronzong: Great Bulk and several offensive options.
Gallade: Great Attack, good Special bulk, and good movepool(Note: Should hold Iron ball)
Musharna: Great Bulk, and High S.Attack
Cofargius: Amazing Bulk, and useable S.Attack
Gothitelle: Good Bulk, Good S.Attack, and good movepool
Reuniclus: Good Bulk, Great S.Attack, and good movepool
Chandelure: Average bulk, Insane S.Attack, and a good movepool(Again Iron ball)
A list of Amazing Pokemon for T-room that cannot activate it(In Speed order)
High Attack: Ferrothorn, Gigalith, Snorlax, Sudowoodo, Steelix, Carracosta, Rhydon, Rhyperior, Golem, Granbull, Marowak(when holding Thick club), Armaldo, Conkeldurr, Druddigon, Azumarill, Donphan, Aggron, Tangrowth, Eelektross, Beartic, Machamp, Ursaring, Cacturne, Crawdaunt, Golurk, Boufallant, Torterra, Rampardos, Scrafty, Swampert, Tyranitar, Scizor, Emboar, Heatmor.
High S.Attack: Tangrowth, Eelektross, Ampharos, Cacturne, Magnezone, Glaceon, Emboar, Heatmor.
As you can see there are many Pokemon that work well in T-room. There are even more than this but these are the main ones.