Actually Gandalf had his whole strength the entire time, he was just forbidden from using it in front of the Children of Iluvatar. Just like how the kids at my daycare probably think I can't tell colors apart or find anything, he could solve this whole problem by himself but he knows it's better for their development if he lets them try by themselves.
I was about to say that worked out so well with Sauron, sarcastically, but I looked it up and it turns out Sauron was an Ainur which is basically a full power Maiar, or in other words Sauron is the reason the limits were established, lol.
Well, Istari were not full power Maiar, that was kind of the point. Honestly, there may have been some elves from earlier ages that were stronger than some of the wizards.
I like to think of Gandalf as like how I act with the kids at my daycare. I think the Istarii asking the children of Eru to clean up Sauron's mess is like me asking the kids to show me which bucket the toys on the floor go in. I could do it all by myself, but it's better for them if they do it.
Considering what Fingolfin did to Morgoth, you'd think so. Gandalf claimed he was the most dangerous person on Middle-Earth save for the dark lord himself though, which would imply he still held more power than the likes of Galadriel.
Glorfindel knew that the time of Elves in Middle Earth was coming to an end and he had already killed a balrog, died, and been resurrected so he passed the torch to Men. Props to him for that