Anyway, I've recently tried Goruggo on my sun team and he is a nice addition. Loses his water weakness while providing a resistance to rock (which is useful should you run Chairzard, Urgamoth, or Jumpluff like I do). Should you be running stealth rock, then he becomes a good spin blocker for a lot of common rapid spinners. He handles Starmie and Tentacruel in the sun with ease for example, which is something that Desukan, Dusknoir, and Dusclops can do...but the difference between guruggo and the other three is that he isn't huge shandera bait.
This could be particularly useful for more defensive Sun teams (like you suggest below) however in general I rarely stack any more hazards than SR to break sashes/sturdy on offensive teams. Pretty interesting how he becomes much better in Sun and is useless as a blocker in Rain XD.
Anyway in terms of the Rock resist - if you don't need a spinblocker too - try Regirock. Pretty much no unboosted physical attack can OHKO him, he can set SR, and also takes Fire attacks like a boss.
Let's talk about sun stall. Although mainly an offensive weather, what might sun stall have going for it. I currently run Dual Screener leaf gaurd meganium and its truly effective. My main three moves are reflect, light screen, and dragon tail but I'm experimenting with the last slot. I've also played around with using giga drain on growth tangrowth and venusaur.
This has got me interested in trying Sun Stall. I really would go with Synthesis for the last move if you want to be doing a lot of phazing (especially if you already have T-Spikes). Beware of pulling out TTar etc, however. Giga Drain is fantastic on Venusaur in particular to recover from LO recoil and residual damage, in my experience.
What are some good leads for a Drought?
Someone recommended a Genosect lead a few pages back - I run a Forretress lead which is bulky as hell and is pretty effective at SR setting and spinning, as well as having Volt Change to get Tales in.
I don't see many Exeggutor outside of supporting ones with a Powder and Sunny Day. I think most of the Cholorphyll sweeping is done by Venusaur and Victrebel, from what I've seen. Maybe it's because of Power Whip and Weather Ball. After all, Venusaur can actually beat a Heatran without a Balloon thanks to Earthquake.
Mebukijika is amazing, try it - it outspeeds literally everything except Jumpluff in Sun, and has pretty good coverage with Normal, Fight, Ground, Grass and Bug options, as well as SD. Tangrowth is fantastic too - can take Hippowdon/TTar/Politoed out of Sun if need be, its just very slow.