Sauron - Physical form in The War of the Ring or not?

[Orofacion of the Vanyar]

Gandalf observed certain rules that limited the power he could display in Middle-earth.

Observed or was forced to abide by these rules. The Istari are Maiar in human forms, and therefore were lessened in their power. Don't you think Saruman would have used his real power if he could? I believe they had no choice in the matter.

In the form he was in, Sauron was the strongest at that time. It's not just a matter of one being's sole power, but his influence as well. Sauron had in his possession the nine, which Gandalf had a time dealing with just the Witch-King, spies, orcs, Uruk-hai, Oliphants, Black Numenoreans and Haradrim to name a few. It's not just the one being that is powerful, but all under his control.

Gandalf was one being who controlled no one openly. His influence was great yes, but his sheer power was not equal to Sauron's.