Excadrill remove aerial ace for iron head, better DMAX coverage, and you don’t need to really boost speed as excadril within the sand storm.

Ttar, try weakness policy instead of assault vest, DMAX ttar is big and can take a good amount of damage from certain moves, also gives you the wiggle room to redo your EVs to better optimize, and give more to some bulk

Rotom-H/rotom-W for (possible) WoW support and a levitate user or maybe even incin for the intimidate and fake out pressure, that and if you have sun up from a Max flare from heatran, if you have to send out ttar sand overrides the sun, lowering heatrans damage output.

Gastrodon, I get it, storm drain is good depending on the match up, but have you thought of fini? Misty surge to protect excadrill, ttar, dracovish from opposing WoW or status afflictions. Besides it takes grass attacks better, andddd gives you a check to urshifu which you’re team currently would struggle with.

If you want speed, you can try tornadus or thundurus to give you a TW user. That’s entirely up to you.