As for how powerful these gods were we can't really say how powerful they were and how powerful the heart of Y'shaarj is. But Y'shaarj is the only god that was killed by the Titans and all other gods were only imprisoned because of what Y'shaarj's death has caused to Azeroth. I would assume that a fully functional old god that is regaining its full power is more powerful than the heart of an old dead god.
You pitiful non orcs dont stand a chance against the mighty Garrosh Hellscream
But in all seriousness and its something that garrosh shouldve seen it doesnt matter if you turn everyone one of your soldiers into a juiced up killing machine you are still gonna lose by attrition
Its just simple numbers its like if the US government injected each of there soldiers with go go juice it would make them the perfect warriors but they still would be up against the rest of the world and they still would lose soldiers to a point where a war of attrition would make him lose
Unless garrosh new toy makes his soldiers invunerable where they simply cannot die he will lose if he is up against every other race on the planet
This whole thing is fucking retarded it doesnt matter how much you can make your soldiers strong if you aint got the numbers you will lose in the end
OK yeah garrosh has lost his mind i accept that but hey im gonna RP where my toon dies by his side Lok'tar Ogar
Well for one story wise you are the greatest heroes on Azeroth, we've defeated some of the greatest threats to our way of life and the entire world before, but because we had the help of some greater person or power in order to really make it work. Defeated Illidain with the help of Akama and Maiev, Defeated Kil'Jaden with the help of Velen, Defeated Arthas with the help of Tyrion and Yogg'Saron with the help of the watchers, we took down the Firelord with the help of the greatest druids on the face of Azeroth and stopped The Destroyer with the help of The Aspects and Thrall. While we are a pretty impressive force to be reckoned with we need help to defeat these large villains. My guess is we will have the help of the some of the larger named members of the Alliance and Horde to take down Garrosh once and for all.
Although we didn't kill Arthas, he toyed with us, insta-gibbed us and it was Tyrion with the Ashbringer who struck him down when he was vulnerable.
Deathwing, lorewise, should be able to wipe us out in 1 fell swipe aswell, this was weird for us being able to even touch him.
I do know the Dragon Soul was used, but even before that we we're damaging him.
Illidan, again, lore-wise, should've been able to take us.
KJ was also only partly through the well and couldn't harness his full powers, I presume.
Dragons, demons and undead aren't that strong I guess.
I have no clue about Loa Gods etc..
We aren't that strong, a lot of help from outside was necessary and we never would've made it against a lot of enemies if it weren't for them.
EDIT: Garrosh is already very strong, his ancestors being able to 1 shot a Pit Lord, he has a strong weapon aswell [open for dicussion if it's the actual gorehowl], him being empowered directly with old god remnants and maybe several other demonifications he might've had in Ragefire, he can rise to be quite a strong opponent.
Maybe not Deathwing or Lich King strong, but hey, they were able to one shot us.
Maybe we don't beat him and we lose
We become the old powerful Horde once again! and we keep trolls locked up in cages!
One can hope
These bosses do extraordinary things. Sometimes, they do way more than even a hero like Thrall could imagine doing (though Thrall's story has gotten pretty out there in terms of preternatural ability). That we weaken them up for the bigger hero seems to me that we're a vital force in this fight. Without us beating these dudes up, Thrall and the like would never have the chance to swoop in and Dennis Rodman the fight.
If it were so easy for Thrall and Tyrion and Maeiv to do what it is they do at the last 10%, Blizzard would never need to write us into the story at all. They could create a total separation between the player and monumental events like the death if Illidan.
We need to distract the big bad, so that our plot characters can prepare their uber-wtf-pwnage beam/missile/attack/whatever to do the bad guy in.
We are needed, we are strong, but we're not the ones who put the baddies down.
We fought C'thun, Yogg'saron, Deathwing the Destroyer, The Lich King, Illidan and KIL'JAEDEN FOR CRIPES SAKE! I think we'll be ok dealing with Y'shaarj infused Garrosh.
We're merely the distracting a lot of the time, it's a super strong plot character with a special item [Dragon soul, Ashbringer] who actually puts them down.
Through teamwork we manage to show our strength and valor, but then the baddies laugh and brush us off.
We couldn't have killed Arthas nor Deathwing without their help.
As for the old gods; They weren't at full power, they are of equal or greater power than titans if truly 'charged up'.
Up till now, Broxigar The Red with the help of a special axe made by Malfurion in order of Cenarius was able to merely make a small wound on Sargeras, would you really think we are much stronger than Broxigar? At most I say we're about equal, we have special items aswell, and we have grown in strength over the past years, but we're not capable of actually killing any old god, lich king, deathwing and doubtfully Illidan.
Although not prominent, Akama helped us defeat Illidan I think.
And Kil'Jaeden... well, yeah, I think because he was still 'stuck' in the portal, he couldn't unleash his full devastation, we merely pushed him back.
Kil'Jaeden: Sunwell Plateau merely a setback!
Also, Kil'Jaeden is just an Eredar infused with demon powers, much like Garrosh is just an orc with Y'Shaarj's powers.
EDIT: Not just Akama, also Maiev helped us defeat Illidan.
Kil'ruk the Wind-Reaver says: Before your history began, our empire was vast. We shared this world with our sister kingdoms, Ahn'Qiraj and Azjol-Nerub.
Kil'ruk the Wind-Reaver says: Our Gods were many, and powerful. We mantid worshipped the seven heads of Y'shaarj.
Kil'ruk the Wind-Reaver says: Great was the Old One, and terrible was His wrath. He consumed hope and begat despair; He inhaled courage and breathed fear.
Kil'ruk the Wind-Reaver says: When the usurpers came - the ones you call "Titans" - Y'shaarj was destroyed.
Cannon lore has stated that the Titans didn't destroy the Old Gods because their survival was tied to Azeroth. That implies that the Titans clearly had the ability to wipe them out but chose not to. I don't believe it has even been stated that full Titans were fighting the Old Gods, rather than Titan watchers like Thorim, Hodir, etc. It makes sense though that if a full Titan like Norganon can shape worlds, and the Old Gods are (for what we have been told) unable to even leave Azeroth, that Titan >>>>> Old God. OG's are certainly among the most powerful of foes that we have encountered in the game, but there is nothing in the lore that suggests that an Old God is a match for a full Pantheon-member Titan.
There is difference between their strength though.
Old Gods usually corrupt and have great mental powers, since Titan's are, I think, Constructs themselves, they might be immune to the corruption in it's purest form, unless ofcourse, like Sargeras, you start doubting and with that showing mental weakness, the Old Gods can totally corrupt them.
I guess the Titans could just re-originate Azeroth and everything's done, or kill the old gods and kickstart life anew on Azeroth.
One thing I wonder, if the Titans are the creators, where did the Old Gods come from? How do they manifest? How do they stay away from the reaches of the Titans? Does anyone know this?