Let me have a look
Seeing you're playing a sandstream team you really need that Hippowdon as your main lead.
That said, its set is quite allright. I'd personally run Yawn or one of the Elemental fangs over Roar. I'd pick Yawn most of the time, except when fighting Titania I would have FireFang ( I have a sneaking Suspicion she will have a Ferrothorn).
So if that is your lead, with leftovers, you're good there.
Now a huge problem with weather teams are A) Other weather setters (though I'm assuming Titania/Hardy wouldn't really change Sand but Amaria would?), or B ) Weather nullification (Defog/ Cloud Nine).
The latter wont be happening all that much I recon, but you never know. So its important to keep your Hippowdon alive for now.
As for our current state, you could get another sandstream user in Gigalith. Most weather teams generally tend to have two mons setting up weather. Gigalith is mostly used as a Lead as well, though I suppose you can make Gigalith the lead, while making Hippowdon the secondary sandstreamer (effectively freeing up a moveslot in taking off Stealth Rocks). Otherwise you kinda need another pokemon that has Sandstorm as a move (with the accompanied item to make sand more durable).
That said.
Sand teams generally have a problem with
Fighting Types (when using Rock/Steel)
Grass types ( More so physical ones)
Ground types (See fighting types)
Water types (See Grass)
Ice types ( somewhat).
So when building teams, you need to consider how to deal with this.
Gliscor deals with Ground/Fighting types though I would preferably run another set.
I'd personally rather run the following:
Gliscor @ no item - Sand Veil
Acrobatics
Knock Off
Sword Dance
Ice/FireFang/Thunderfang/Sky Uppercut ( really depends on what you need @ said point
Acrobatics deals nicely with clearing off Fighting Types (and one if not its only STAB). Hence you dont want an item.
Sand Veil gives you a better synergy with sand than Poison heal in this case
Knock off is nice to have, and you can hit Steel/Rock types with it, same can be said for Sky Uppercut tbh. So both are good for Titania/Hardy.
SD is always nice to boost yourself up.
The last is just filler/coverage.
Swampert is also really good for this team, though I wouldnt run that set.
I'd go for a more offensive set.
Waterfall
Earthquake
Rock Slide
Protect.
Protect helps with scouting out your opponents moves. Rockslide/Earthquake gives you a Pseudo EdgeQuake combo and Waterfall (or surf) is there for STAB>
Excadrill is fine, can take advantage of the weather
Change I would make is Sword Dance over Dig.
Versus Titania/ Hardy I would give it a Balloon instead of Soft Sand.
Magnezone can be fine against Ice/Grass types. Same for Lucario.
So those fit really well.
Metagross also really works well.
This is somewhat Gimmicky but can possibly help with Amaria (granted it doesnt also have an ice move)
Cacturne @ Water Absorb/SandVeil - Leftovers
-Spiky Shield
-Leech Seed
-Substitute
-Energy Ball.
A bulkier version without Water absorb, that can also be used for Titania would be Chessnaught
Chessnaught @ Leftovers - Bulletproof
-Spiky Shield
-Leech seed
-Substitute
-Hammer Arm / Seed bomb ( I prefer Bomb over Hammer because it gives no Recoil)
Hope this helps!