I rescued two albino oscars from the pet store about two weeks ago. They have been in a small 5 gallon hospital/quarantine tank. I now have an empty 25 gallon, but it is not cycled. I know they need good water params to keep them from getting hith, but a 5 gallon is awful small for them. They are only about 2 inches long, but would it be better to keep them in the 5 gallon cycled tank or put them in the 25 gallon that I just started up and is not cycled?

I would put them in the bigger tank and keep a close eye on the levels. Though at 2 inches they are going to outgrow the bigger tank in less than a couple of months. You will be looking at at least 75 gallons when they are 5 inches each and after that around 125 gallons for two.

I do have a 125, but I have to move other fish around and get another filter to add to the tank. Right now it has my 3 small koi that will go into a pond and a medium sized male convict cichlid that will go into the 25 gallon. These were rescued oscars and I didn't have anything else empty to quarantine them in except the 5 gallon. I have read that they are very hardy fish but I have also read that they will get hith disease if the water is not kept in excellent condition. So are they delicate fish or are they hardy? I do very well with keeping my water params as close as possible to what koko says.

Oscars are robust fish and when kept properly they thrive very well. They dont really mind what kind of water they are in ph and hardness wise.
Sounds though they are going to have a great life with you