All you need is a regular bank account from any bank or credit union, unless your state has some unique requirement I'm not aware of. https://www.nolo.com/legal-enc...You would do well to purchase "Every Landlord's Legal Guide" by NOLO.

We’re looking for a duplex to HOUSE HACK as our first investment deal but after looking for a year and making 3 competitive offers in the last couple months we just haven’t been successful in scoring a property.

This is our first non-weekly rental unit and I was wondering what other landlords do regarding credit scores and background checks, ie what are your minimums? 

Avadian Credit Union is 3.375 to 3.625 depending on if you want to pay origination fee.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

As far as your particular scenario and investment please provide more color like down payment, appraised value, type of property, how long you plan to hold it, your credit score, your experience etc….this type of info is necessary to give you a good idea as to what would make the most sense in your scenario.

If you go the non-bank route (like a hard money lender), you'll be able to get a 30 year fixed against a duplex at 20% down and the rate would likely be 4.5% - 5.125% depending on your credit score and the property's/loan's characteristics. 

@Jason Wray one is a local credit union and the other one is Neat loans, an online mortgage broker.

Is it even a possibility not to have our credit scores checked. 

I am trying to help them help themeselves, I've sent them several apartment links in their price range, however, low income and mid 6 credit score has resulted in 2 application rejections in the last 2 months.