Re: Sun teams are good too
You're right about Sun teams being good, the issue is that Rain and Sand teams being better and a hell of a lot more common. Tyranitar, Politoed and Hippowdon featured on almost 40% of OU teams last month, making them an extremely common threat you'll need to prepare for. Anyways;
-255 EVs should be changed to 252, any EVs that take the total above a multiple of 4 are wasted. The 6 lost EVs could be put into raising another stat by one point, and every little helps!
-Ninetails isn't beating Tyranitar, it will underspeed you, get sand going and laugh in the face of your HP Fights (You'll 3HKO at very best, and it will just set up SR then KO you with Stone Edge). Go with the standard Special Defensive lead, using Will-O-Wisp to neuter tyranitar will make it easier to switch into it and reset your Sun at a later point in the game.
-Go with 252HP/252Att/6SpDef on Donphan, maxing HP is almost always the best way of improving general defence, unless it has a very high HP stat in the first place. Ice Shard over Seed Bomb, I have no idea what it's meant to be doing and it offers better coverage alongside Earthquake, as well as mauling the OU Dragons and Gliscor.
-U Turn or Close Combat over Earthquake on Infernape, EQ offers practically identical coverage to Fighting Type moves without the benefits of STAB. CC provides a more powerful attack than Mach Punch, while U Turn facilitates scouting.
-Sawsbuck needs Swords Dance or Choice Band to function as an effective physical sweeper, Base 100 Att is just too low in OU if you aren't going to boost it. If you do decide to go for SD, put it in over Jump Kick. And a quick heads up, Nature Power changes based on the location, not the weather. In wifi conditions, it becomes Earthquake.
-You're overestimating the power of Thunder Punch on DNite, it doesn't handle many of the OU Water types all that well;
*Cloyster survives a +1 Thunder Punch with ease as it sets up Shell Smash, then obliterates you with Icicle Spear (Which bypasses Multiscale)
*Gyarados will go down unboosted
*Politoed will put you to sleep with Hypnosis as you set up.
*Rotom-W is neutral to Electric and will happily burn or paralyse you.
*Starmie gets beaten, unless it's a trick scarf variant who will 2HKO you with Ice Beam.
*Tentacruel is better handles by Earthquake
*Jellicent will take a +1 TPunch then burn you with WoW or Scald
*Swampert is immune to TPunch.
Switch Dragon Claw out for Outrage, which hits harder after STAB than a Super Effective TPunch (180 vs 150), and put in Fire Punch or Extremespeed over Thunder Punch.
-I'm confused as to why you'd be using Ancient Power against Bugs and Flying types, both of whom are hit harder by Flamethrower and HP Ice respectively. That pretty much leaves Volcarona, who is most often seen in variants that will set up in Heatran's face (Quiver Dance+ChestoRest being the most common). I'd honestly switch it out for something more useful like Dragon Pulse, but between the other 3 moves coverage is relatively solid so it's up to you really.
Aside from the above changes, it's generally quite a solid sun team. My only issue is that other weather, which as mentioned before is extremely common, is going to screw you over big time. The three other weather starters (well, the three decent ones) can all happily switch in on a lot of your team, and you have no real means of hard countering them. I would personally bring in a mixed Virizion;
Pretty much a solid counter to Tyranitar, Hippowdon and Politoed. Resistences to all of their STABs makes for easy switches, Close Combat annihilates all standard TTar (Even with the -Att nature), and the other two can be set up on and KO'd with boosted Giga Drains. Once they've been cleared out you can happily bring the sun out for the rest of the game. Try it over Dragonite, three physical sweepers is hardly necessary and Infernape's Mach Punch will be a lot more useful, particularly when it comes to taking on Excadrill.