Marowak is a nice pokemon under trick room, and you should replace the Adamant nature on your Excadrill to a Brave nature. Here are other pokemon who do well under trick room: Conkeldurr, Metagross, Gigalith, Octillery, Emboar, Bisharp, Druddigon, Scizor, Ursaring, Breloom, Heatran, Exeggutor, Tangrowth, Vaporeon, Magnezone, Chandelure, Darmanitan(Zen Mode), Eeleketross, Rotom-A,
No Escavalier? Under TR, he's "faster" than opposing Renniculus and can OHKO with STAB Megahorn. Furthermore, he has Pursuit. Max HP no def makes him take only around 60% from a Latios Draco Meteor while he one hits it with Pursuit. High attack and no speed just screams Trick Room.
Also, any attack aimed at Bronzong is not resisted my Excadrill. Fire attacks are what are usually aimed at him, which is definitely not resisted by Excadrill. Why doesn't Bronzong have Gyro Ball?? It threatens other Sand Storm teams and Chlorophyll sweepers so well.
On Slowking, I would replace Nasty Plot with Flamethrower to hit things like Ferrothorn. Which also reminds me that your whole team is very weak to Ferrothorn. It can switch in and "outspeed" everything under TR conditions if it's Sassy and 0 Spe IVs.