As with any sand rush excadrill team, sand support was required. i went with CB Tyranitar as opposed to Hippowdon thanks to its ability to more readily check broken Heatran (especially firium-z sets), trap or eliminate Zapdos, a rising threat that acts as a roadblock for Excadrill, and to generally open holes during the early-to-mid game for Excadrill.
Looking at this core, it was blindingly obvious that a solid Kartana+Water spam check was required; enter AV Amoonguss, which is one of the most liberating changes to happen to the team thanks to the decline of Zard-Y (which meant no Pex was needed). people also have a tendency to double from opposing Koko into an offensive Water anticipating your Excadrill to come in, so you can use this to your advantage with a well-timed prediction and grab momentum with Amoonguss. from here on out, the rest of the team was just rectifying issues i found with the SM iteration of the team, such as, but not limited to: an over-dependancy on Spikes Gren+Tyranitar for breaking common balance cores, as matchups such as that had to be played perfectly and were often drawn-out ordeals.
Firium-Z Heatran was added to mitigate issue with Toxapex cores and act as a general balance breaker+secondary steel. Firium-Z is cool because ladder goons never, ever Earthquake Heatran with Lando-t when you have your own Lando-T, so you can nuke them and get them out of the way for excadrill asap. Furthermore, if you know it's defensive Lando, just click that shit and send it packing. This is also the team's only real way to properly apply pressure to Mega Sableye, so try to get as much value out of it as you can vs fatter teams. Baiting in Gliscor to aid Excadrill is also important.
Threw on a defensive lando-t as the team's ground resist, which is obviously mandatory with Heatran+Tyranitar+Excadrill, and general physical sponge. Went with Toxic to stop the team completely folding to broken Hawlucha, as with that+sand residual you can limit the damage it can do. You can also nab Zapdos, M-Latios, and Tangrowth with Toxic, aiding Excadrill even further.
Last up, I needed some sort of speed control outside of Excadrill in sand, as the team was abysmally slow. Scarf Protean Greninja is a great fit for a multitude of reasons, such as: it revenge kills Volcarona without forcing you to basically sack Tyranitar, it synergises amazingly with Magma Storm Heatran thanks to the pokemon it tends to U-turn on, and it also provides Spikes, which is amazing on a team with Rapid Spin in USUM.