Thats fair enough :) I know that it is frail etc and that Thundurus is better but I like Heliolisk and I thoroughly dislike Thundurus in this generation (although this probably has something to do with the swagger sets more than anything else), and I knew it was a long shot to ask for Heliolisk. Hopefully when the UU contributions begin I can reserve Heliolisk and Mienshao :) -speaking of which, now that UU isnt beta anymore, when will the analysis writing begin?Here's a tl;dr explaining why Heliolisk should not get an analysis:
Heliolisk has already been rejected once in the past, and for good reason. It's just an overall very mediocre Pokemon. Its physical bulk is awful to the point that even resisted hits do a ton of damage (i.e. Talonflame's CB Brave Bird has a small chance to OHKO after only Stealth Rock damage, while SD Talonflame's +2 Brave Bird is an outright OHKO), and its special bulk isn't anything special either. Its power isn't too impressive either; Life Orb Heliolisk hardly has any chance to 2HKO SpD Heatran with a super effective Surf after Stealth Rock, for instance. It also struggles to get by a whole host of special tanks and walls such as the blobs, Mega Venusaur, and Latias, unless it runs a specific Hidden Power type (which is struggles to find room for when it's also trying to run Thunderbolt/Surf/Grass Knot/Focus Blast/Volt Switch).
More than anything, it's just so overshadowed by the amazing Thundurus that there's little reason to use it. Its only real advantages are a lack of a Stealth Rock weakness and a Water immunity or an extra power boost in Sun via Solar Power. The Stealth Rock neutrality isn't even that big of a deal. Stealth Rock is easier to remove than ever thanks to Excadrill and the unblockable Defog, and it's not like Heliolisk enjoys losing 1/8 of its health switching in either (not to mention it's vulnerable to Spikes). Its terrible bulk means it's not surviving many attacks anyway even with the extra health.
Dry Skin is useful and all, but you're really blowing the ability to switch into Water attacks out of proportion since many common users of those moves are really risky switch-ins. For instance, Gyarados is generally going to Sub or DD as you switch in and KO the next turn with Earthquake, Greninja outspeeds and 2HKOs if you switch into anything bar Hydro Pump, Azumarill pulverizes you with Play Rough or Superpower, Cloyster just Shell Smashes on the switch and then eats you alive, and Keldeo wins if you switch in on Secret Sword, Calm Mind, or Expert Belt Icy Wind. Besides switching in easily on Rotom-W and checking BellyJet Azumarill, Thundurus can take on pretty much all the Water-types Heliolisk can even more easily.
Solar Power isn't a huge advantage either. Heliolisk doesn't really offer much to Sun teams synergy wise, and while it's very powerful with a Solar Power boost and Choice Specs, Sun teams already have huge amounts of power with Fire spam from Pokemon like Victini. Sun teams are already hard enough to use since Ninetales sucks and Charizard Y's Sun doesn't last that long (not to mention it's more interested in abusing the Sun itself rather than supporting teammates), so it's not a huge niche even then.
Meanwhile, Thundurus has a lot of significant advantages over Heliolisk. Its extra 2 base Spe points are pretty important since they let it outpace Latios, Latias, Espeon, and Gengar, each of which can outspeed and deal a ton of damage to Heliolisk, if not outright OHKO. Thundurus has almost identical special bulk while also having significantly higher physical bulk, which lets it check things like Talonflame and Mega Pinsir much more easily (for instance, Sharp Beak Talonflame's +2 Brave Bird can't OHKO Thundurus from full health, while its +2 Brave Bird with no boosting item almost always OHKOs Heliolisk). Thundurus also has not only a higher SpA stat, but a higher Atk stat as well, letting it attack effectively from both sides of the offensive spectrum. This adds a whole new dimension to Thundurus that Heliolisk doesn't have, and it gives Thundurus a solid unpredictability factor. While it has a pretty similar special movepool to Heliolisk, Thundurus has the option of running Nasty Plot to muscle its way past bulky Pokemon that might otherwise wall it, while Heliolisk has no good boosting moves whatsoever. Thundurus also has a plenty wide enough physical movepool to make good use of mixed and physical sets, and Defiant makes it a solid Defog deterrent and a terrifying physical sweeper once it gets the boost. Prankster gives Thundurus extra utility on its special sets as well, letting it stop any non-immune sweeper with priority Thunder Wave or stop any status moves with Taunt, regardless of the opponent's speed (mainly looking at Deoxys-S here).
So to sum up, Heliolisk is very frail, not very powerful, has coverage issues, and overall just faces too much competition from Thundurus (and that's still ignoring other offensive Electric-type Pokemon that give it competition). There's a reason it's unranked in the viability thread. It's just too outclassed and decisively mediocre to be a good choice in OU.
Thanks and have a nice day.