1. There has been no testing done.
There was actually testing done with Sun Stall, I know for a fact that Lavos reached #1 on the PO ladder not too long before PS! became the primary Simulator, and while that was before the days of BW2 it shows that this team type can be effective. Obviously now with all the new Rain threats on steroids (Keldeo, Genesect & Therians), Sun Stall may seem very unviable in this current metagame, but thats wrong. We all know that Lavos is a good, and established player and team builder, so there may be a lot of people thinking that just because he can do it doesn't mean that the community can, and that perhaps it would be him leading the project, with the majority of the community blindly following. That too is wrong. While I am a relatively unknown player, I have recently made a Sun Stall team, and had great success with it, against almost every style of team in the current metagame, that includes all those Rain Offense teams. As I have played the team across numerous alts, I do not have a top 10 ladder ranking to back this up currently, but I promise you I am not speaking with nothing to back me up. If I can build an effective Sun Stall team, I think that the community will be able to quite easily. To extrapolate on that; I am a much more offensively minded player, and I feel a lot more comfortable with teamstyles such as HO, I really don't like slow matches with weaker offensive Pokes, however when I saw the discussion in this thread I wanted to see if I could come up with an effective Sun Stall, and I did.
2. Sun Stall is not worthy of usage.
You say that you believe underused should only apply to strategies that deserve more usage, and that Sun Stall does not deserve more usage. How exactly does that work? It is a viable strategy just like any other, granted their may be a stigma about it that only very high level players can use it well, but I'm no high level player, and I have both made, and used one well. I think that it is sort of unfair for any one group to be able to determine exactly what types of teams 'deserve' more usage, I think people should be allowed to use whatever they want without having to justify it to the world. Unless of course they wish to get into discussion as to why the team is actually good, then they would obviously be required to give further details and information. I believe that over the past few pages of this thread Lavos, and others, have done quite a good job of that.
3. There are only 15 viable Pokemon.
The next point I will address is what was said in regards to there being "only 15 viable Pokemon for this team type". That is quite far from the truth. I will admit that at first that is exactly what I believed, although when building and testing my Sun Stall team, I found there was a plethora of options, and not just mediocre ones, good options. You have obviously got to have Ninetales, as that is the whole premise of the team, an then because its a Stall team you obviously need your dedicated walls, Hazards and Spin Blocker. However thats where the musts stop. Yes the vast majority of successful Stall teams also have Spinners, Clerks and Phazers, but those aren't mandatory for success. Personally I am using a Clerk alongside a Spinner and a few Phazers, as I feel that it gives me the optimum chances for success, but I was limited to my own company when making my team, so I believe that as a community we could easily find ways around the aforementioned 'roles' if we so chose. Include to that, the fact that at the designated potions there are a variety of Pokes that can fill it well. Obviously there are those that will be considered superior for certain positions, but my involvement in recent community projects such as the Dark Horse Project, and Counter This Pokemon project, have taught me to never underestimate the creative potential of a collective such as the Smogon community, and by saying that you are limited to any number of Pokes, is doing just that.
4. You must use certain Pokemon.
I would strongly recommend that a Spinner be used, but it isn't mandatory as you said earlier, and while Tentacruel and Forretress are possibly the best suited Spinners for a Sun Stall, there are others to be considered. You have said that using Donphan will compound a weakness to Water, which when facing Rain teams could be a serious problem, but I have to disagree on that. I am not being Naïve in believing that just because Sun halves the power of Water moves, that it eliminates the weakness, I am stating that it isn't necessarily enough of a deterant to not want to use Donphan at all. I'll address the weakness to water separately now. Looking at my Sun Stall team, I have one member weak to Water. Want to take a guess what that is? Granted this is only one example of a Sun Stall team, however it showcases that not all Sun Stall teams will have a predisposition to be at a disadvantage against Rain Teams. Because this is a community project, we will definitely be hearing all sorts of unique ideas and thoughts on things such as the roles that will need to be filled, the Pokemon to fill those roles, and then the movesets those Pokemon will have. This means that we will potentially see some very unconventional sets, that are incredibly effective. Participating in the Dark Horse Project taught me that quite well.
5. You are forced to use Heatran.
Now as far as being forced to use Heatran, that is also really in the opposite direction of correct. Heatran is an incredibly useful asset to a Sun Stall as it can Phaze, it can Status and it can set up Rocks. However it too is not mandatory, I know that it isn't on my team, and I am never left wanting for it. For having a weakness to Fire, I only have one Fire weakness on my team, and that is on the mandatory Steel type that no Stall team should be without. But as I mentioned earlier, just because something should be, does not mean it has to be, and in a community project such as this, I think that must be kept in mind at all times. It is true that if Sun Stall comes up against an offensive Heatran, or any Heatran for that matter, it can have serious problems. The first time I came up against a Heatran I was completely at a loss for ideas, and thought it would just tear apart my team. Then I decided to look at what resources I had available to me. As a note, the most powerful offensive move on my team is Ninetales' Flamthrower coming off 0 Satk EVs, so it's not like I'll be punching holes in anything any time soon. Through intelligent play, and full utilization of the assets the team had, I aptly dealt with Heatran, and the remainder of the team. Since then, I have known how to deal with Heatrans and have done so ever since. I think that speaks wonders for how versatile a Sun Stall team can be, and that there are always hidden gems in the rough, one just needs to understand which tools o use and how to use them to attain said gems.
6. Jumpluff is useless.
I agree with you Harsha in that Jumpluff is pretty useless. When creating my team I spent a grand total of two minutes deciding that it wasn't going to work. As we all know a Stall team requires each of the members to pull its own weight, and outside being an annoying little dandelion, Jumpluff doesn't really do much. As such, it really isn't the best fit for a Sun Stall team, however I am sure that if the community wanted to use one we could find a way to do so effectively. That leads me into my next rebut; Ninetales being useless.
7. Ninetales is horrible, and Cresselia fails against Rain teams.
I can in no way fight that Ninetales is almost dead weight on a Sun Stall team, however it isn't entirely useless. It is beaten 1 on 1 by the other weather inducers, and it lacks any truly decent stats, however it can still be used well. For it to be successful on a Sun Stall it is generally best to run a Specially Defensive set, as that can utilize what defenses Ninetales does have, along with its sightly above average support movepool. It was already mentioned that Ninetales can both induce status' and Phaze, which is quite a useful paring on a Pokemon for any type of Stall team, so while not amazing at it, Ninetales can help the team with more than just never-ending sun.
Whilst on the issue of Pokemon not pulling their weight, I'd like to address Cresselia. Cresselia is the definition of bulky with its 120/120/130 defenses, and it plays the role of a wall incredibly well. While it may have troubles dealing with Rain teams, outside of Rain it is incredibly effective. That said it doesn't become useless as soon as its in Rain, it comes down to what set its running and how well one plays it. In a worse case scenario Cresselia will be able to status, or at least hinder in some way the more threatening members of a Rain team. I will provide a few examples to support this; Example A. A physically defensive Cresselia, so no specially defensive investment, versus the standard 252 Satk LO Tornadus-T. Hurricane deals 40.76 - 48.19%, so provided Cresselia comes in with at least 60% health it can then proceed to potentially status, which can include Thunder Wave crippling Tornadus significantly by taking away its best asset, or hit it with an attack such as Ice Beam to deal a decent amount of damage; 0 Satk Cresselia Ice Beam v 0/0 Naive Tornadus-T: 44.14 - 52.17%, which is a guaranteed 2HKO after Rocks, which will be up on a Stall team. Now if it was a Specially Defensive Cresselia it would be taking those Hurricanes a lot better, although Tornadus would obviously U-Turn out. Genesect can hurt Cresselia with its U-Turns which could be an issue, although Cresselia can happily switch out into whatever the player feels gives them the most options as Genesect will then be able to go into the appropriate counter for the Cresselia switch. So really, Cresselia isn't looking too bad against Rain Teams, both a Specially and Physically Defensive set can cope well enough.
8. Sun Stall cannot match up with the rest of the metagame.
The next point I'll address is what you've said about Sun Stall not matching up well against the majority of the metagame. Once again, thats slightly less than true. I have played the metagame, and in the majority of cases I have won with my Sun Stall. Certain teams will obviously require much more thought, and when I get matched against an opponent with superior skill to mine I will not always win, but when I do lose it is not because my team let me down, more that I was just outplayed which I will happily take. You've mentioned the main threats that BW2 brought, and then proceeded to say that Sun Stall has no business attempting to deal with them. Well if you're running Sun Stall and you are faced with those threats, its not like you can say 'well the team isn't designed for them so I won't deal with them', and have them just go away, you will have to do something about it. So far thats what I have been able to do with my Sun Stall, with certain threats there, Landorus-I in particular, I know I lost the first time I played one of those because I didn't know how to deal with it. However after that loss I figured out what needed to be done, and since then I have not lost to one. You can't ever build a team that doesn't have any business against certain threats, because inevitably you will be faced with them eventually.
9. Genesect & Dugrtio run rampant on Sun Stall.
The last point I will address in your argument is what you've said about Genesect+Dugtrio ruining Sun Stall once Heatran is gone. Well if you're not running Heatran, what then, you get destroyed outright? Well no that isn't really the case. Lavos' Sun team is becoming less and less common, yet I have faced a few of them recently using my Sun Stall, and a few variations on them, and I don't get outright beaten. Dugtrio doesn't do anything to 4/6 of the members of my team, and if I know that my opponent has a weather other than Sun I won't be bringing Ninetales in until I know its safe from Dugtrio, which basically leaves one member of my team vulnerable to Dugtrio. Genesect can also be dealt with through proper utilization of assets. Bottom line of this point; there is always a way to deal with whatever threats arise provided you have built a strong enough team, and with the community working on it I strongly believe this is possible.
Summary.
In summary; I believe that Sun Stall really should not be discounted because it is 'hard' to use or create. I have been able to do so, and there are so many more talented Team Builders and Battlers out there than myself, which means that there is serious potential for this in the community eye. I do not mean to say that you make no valid points Harsha, because you do, although you do make a lot of points which I strongly disagree with, and those are what I have addressed.