Could Sauron have resisted against Ar-Pharazon?
 

If he managed to recruit Durins Bane Balrog, Smaug(assuming he was born in the first age), a handful of surviving fire-drakes both with wings and wingless, Olog-hai, Uruk-hai and breed Shelob sized-spiders. And pre-easterlings and harad armies. Could he with these extra units fight Ar-Pharazon head on and might even win?

I assume that you mean militarily, since he did "resist" by corrupting Numenor.

An in-depth answer to this question is not feasible, since all we know about the relative strengths of Numenor and Mordor is that the former's might was overwhelming to the point where Sauron's forces declined to fight and fled, even though he had the Ring!

So, militarily, the answer appears to be no.

Aside from the addition that getting all the dragons, giant spiders, and the Balrog to play ball was clearly not an option (else why hadn't Sauron done it?), I agree.

It'a safe bet that all Orcs and Trolls were already at his command.

The books tell us that the Dwarves "awakened from sleep" the Balrog of Moria, circa TA 1980, so clearly not a Second Age option.

Smaug could not have been born in the First Age except at the very very end, since the winged dragons only appeared then; rather more to the point he said himself that he was "young" at the time he destroyed Erebor, so I doubt seriously he was around in SA 3200. Of course, there were other dragons, so for all we know Sauron did command some (or not; dragons are hardly team players).

The Numenorean forces were UNBELIEVABLY powerful; so much so that Ar-Pharazon could actually believe he could fight the Gods and win. Think about it: in the War of the Ring, Sauron's minion the Witch-king could drive his orcs in suicidal frenzy, bridging rivers and trenches with their own heaps of slain..... but when the Numenoreans landed even Sauron himself, with the Great Ring, couldn't prevent his Orcs from simply running away at the sight of them.

Imagine the Roman army being confronted by the D-Day invasion force.......

But
 

For argument sake, let's say the balrog, Smaug and a couple fire-dragons were on his side, together with the olog-hai and uruk-hai, the numenoreans would defeat them in battle regardless?

A question for the better memories: does it say anywhere that Sauron actually tried his hardest to win that battle with Pharazon? Did he even expect to defeat Numenor on the battlefield? Or was his plan to get behind the scenes all along, if not in the guise of friend then in the guise of prisoner? I do recall that he was secretly very happy that Pharazon took him to Numenor.

According to the Akallabêth, when Sauron saw Ar-Pharazôn's army, he immediately concluded he had no chance of militarily defeating him. It was only then that Sauron conceived the plot to use his guile to achieve Númenor's end.

I would suspect, too, that Sauron's defeat by the forces sent by Tar-Minastir earlier in the Age fed his sense of hopelessness. After all, Pharazôn's army was much larger.

This is the classic "If my grandmother had wheels she'd be a trolleycar" kind of argument.

Or rather, it's a set of equations with too many unknowns.

How many dragons equal one balrog? How many orcs equal one dragon? Are uruk-hai double a regular orc, or 2.5 times, or 6.33 times one orc?

So now that we've got that sorted out, and we know how many dragons and orcs and so on Sauron had available, we can calculate that Sauron's maximum potential army equals 10**8 orcs, or the equivalent of 10**2.8 dragons.

Great. Now moving on, we have to calculate the Numenorean force. They only had warriors with swords. And they didn't have a humongous population. But we need to be precise, so fortunately, we have unknown-sourced information that Numenor had 4.6 x 10**5 warriors. Now we know that these forces scared the daylights out of all those evil forces, so by definition, 4.6 x 10**5 Numenorean warriors > 10**8 orcs. Doing the math, you get that each warrior equals --- maybe someone else will do the math.

But in any case, each Numenorean was worth a few hundred orcs (even Gondorians were worth over a hundred orcs each), and there were enough of them (as we have seen above) to more than equal the number of orc-equivalents at Sauron's disposal in the form of dragons, balrogs and the rest.

So, based on pure math and reliable equations, you have your answer.

This approach also works with questions like "If there were more lions in the Serengeti, would the elephants have a chance, if there were also more elephants?"

They also had lethal archers, armed with steel bows.

I sometimes wonder if the films or other elements of popular culture have caused a tendency to somewhat fetishise the forces of evil, i.e. creating a perception that Sauron/Morgoth had these incredible "living weapons" (balrogs, dragons, olog-hai, etc) and therefore must in some strange way have "deserved" to have won (a bit like the pop-history obsession with German tanks of WW2) and that the free peoples of Middle-earth, especially Men, despite their self-evidently strong track record of victories, were somehow weak and pathetic because they're not "cool" enough or something, i.e. "Men are weak."

EDIT: See also the perception of events in Professor Tolkien's legendarium as being dictated by "power levels" rather than decisions, fate, chance, historical forces etc., as if, say, Sauron put 3000 pts of miniatures on the gaming table and his opponent only had 2000 or similar.