Basically this is just an attempt to correct what was once my old sunny day team to be more fitting for current metagame. I came back recently after a long break and was like whoa wtf my team's not doing so well anymore. It's highly unlikely I'll take it once complete/ if complete and play nonstop; it's just nice to know you have a decently bulit team you can play from time to time if for some reason you feel up to playing.

Anyways before any suggestions, I do have some criteria I'd like to keep for this team. Must be at least half UU/Nu. Must keep Exeggutor and Jumpluff. Other than that it's free play I guess.

Mohandas (Uxie) @ Light Clay
Ability: Levitate
EV Spread: 252 hp/ 180 defense/ 76 speed
Impish Nature
- Reflect
- Stealth Rock
- Sunny Day
- Uturn

George (Infernape) @ Life Orb
Ability: Blaze
EV Spread: 4 hp/ 252 attack/ 252 speed
Jolly Nature
- Close Combat
- Flare Blitz
- Stone Edge
- Uturn

Brett Favre (Dusknoir) @ Leftovers
Ability: Pressure
EV Spread: 252 hp/ 28 attack/ 228 defense
Impish Nature
- Earthquake
- Pain Split
- Sunny Day
- WilloWisp

Pesto (Exeggutor) @ Life Orb *shiny for golden goodness*
Ability: Chlorophyll
EV Spread: 4 defense/ 252 speed/ 252 special attack
Modest Nature
- HP Fire
- Psychic
- Solarbeam
- Sunny Day

ManningFace (Heatran) @ Choice Scarf
Ability: Flashfire
EV Spread: 252 speed/ 252 special attack/ 4 special defense
Naive Nature
- Earth Power
- Explosion
- HP Ice
- Overheat

Pillow (Jumpluff) @ Leftovers *shiny for pink awesomeness*
Ability: Chlorophyll
EV Spread: 4 defense, 252 speed, 252 special defense
Jolly Nature
- Leech Seed
- Sleep Powder
- Substitute
- Uturn

Basically an attempt at a decently offensive but adaptable sunny day team. A couple different mini-strategies can be used throughout the course of the battle. There's always just the plain sunny day and sweeping with exeggutor/heatran, then there's infernape for late game sweeps. But there's also a little element of stall with stealth rock in place, a couple will-o-wisps in place and subseeding jumpluff. Jumpluff also fills a nice niche role. If I encounter a wall/type in which my sweepers can't ohko or 2hko, or if I encounter offensive threats that would outspeed and ruin my 2 bulk pokemon, I'd send jumpluff to force a switch or annoy away with subseed. With 3 pokemon on the team knowing Uturn, predicting becomes a bit less of a pain, while still keeping an offensive pace for your team. Uxie is nice for setting up stealth rock/sunny day/reflect and is just a general bulk pokemon for taking hits when needed. Dusknoir plays the same role as well. Heatran also doubles as a good revenge killer.

It's a decent team but probably wouldn't stand a chance against well put-together teams with all of the top of the top OU pokemanz, but it won't go down without a fight.
I'm still debating rather Heatran should stay with his choice scarf build or if he should focus more on sleeptalking strategies while behind the buffer of reflect.

For those who like all OU teams/teams with more buff, Cresselia in place of Uxie provides better bulk and recovery (also countering dragons rather well), while Breloom could possibly replace Jumpluff (although 700 speed jumpluff is a novelty). Sadly Exeggutor doesn't really have a replacement when considering he gets majorly buffed from sunny day-- and this is a sunny day team. However Tangrowth can also be considered an option to replace either jumpluff/exeggutor for those looking to want more buff.

I guess the main concerns here are possible dragon types and tyranitars.

You have a real Heatran weak. Nothing can switch in on it safely and Exeggutor, is completely walled by it.

Uxie is a decent lead, but with all the faster Taunt leads running, around you are in real trouble. However, I do not see any other lead that can effectively set up a weather effect. I've heard that Aerodactyl can do it fairly well. He's fast and hits hard, but not as bulky.

I am not familiar with Sunny Day teams, but there are only two Pokemon on your team that take advantage of it. Also, why Overheat instead of Fire Blast?

I'm surprised you do not have Tangrowth on this team. He can be a real beast on a Sunny Day team. I would rather have him than Exeggutor, but you don't want to change that so ignore it.

Since you sort of have a stall aspect in Jumpluff, I would like Toxic Spikes over Stealth Rock as TS is more for stalling than SR is.

Weird EVS on your Jumpluff. I would much rather have 252 HP than 252 SpDef.

Only two Pokemon are needed to set up Sunny Day, three is overkill and overly cautious. You just need to be smart in what you do and play wisely.

Anyway, I hope that little bit helped. I don't use weather teams so that is as much as I could offer.

Keep in mind any sunny day team has a weakness to tyranitar, heatran or dragons-- some more than others. Even all OU teams are scared of such common tacky OUs to the likes of salamence tyranitar or heatran.

I already mentioned if you're looking for more buffness in the team you can replace either jumpluff or exeggutor for tangrowth. Tangrowth gets 2/3s recovery in the sun, while his stab power whip ohkos tyranitar and earthquake ohkos heatran. 228 speed EV'd speed plus natured tangrowth in the sun also outspeeds speed plus natured choice scarf heatran with max speed EVs. Getting a good hit off on heatran with tangrowth will most likely be the result of good anticpation with uturn or just blowing through with a sweep hopefully.
Cresselia is an option over uxie for countering dragons-- but uxie does get the advantage with access to stealth rock and uturn. (Both of which are crucial to offensive teams)

Uxie's Uturn lessens the effect of taunt to some extent but you will take one hit at worst. Luckily Uxie has good bulk.

And no, 4 pokemon on my team take advantage of sunny day-- not 2.

I tend to disagree with toxic spikes being advantageous over stealth rock for jumpluff.
1. toxic spikes is limited to very few pokemon who can use it.
2. jumpluff tends to force switches more often, which is where stealth rock shines.
3. This team has 2 potent sweepers in the mix, in which stealth rock is more beneficial to them.
And putting more EVs on jumpluff means less effective leech seeds. Basically jumpluff doesn't want to take a hit to begin with so you're kinda left with half of his EVs that dont serve a purpose.

You are right though, Fireblast is the better option over Overheat for Heatran, as there very well might be multiple occasions in which he wants to stay in for sweeps. I will change that.