You should be fine if you move everything over to the rubbermaid. However, if you don't transfer all the decor & substrate (cleaning/change), you might get a mini-cycle. It is best to monitor levels daily & do pwc
Your fish might be a bit crowded in a 35, but they should be OK for at least a few days. <Ideally, you want something close to the tank size - ie a 50 gal
bucket would be better ... but 35 gal
is close.> You might want to put something in the tank so the fish can hide if there is overcrowding & territorial issues.
I have done exactly what you are proposing with my goldies. They were fine in the tub for over 2 weeks. <Although I had only 6 fish in a 30 gal