Most brokerages have company web sites that have all Active listings that are accessible by the general public.
It would be very unlikely that you could get full access which would show you sold information, Withdrawn information and many will not give access to those properties that are pending or have Contingencies.
If you need / want full information... you will have to work through a licensed real estate agent that belongs to the MLS's your interested in. Full direct access is unlikely.
To do investing in MLS listed properties you will need to be working with an agent... find and develop a relationship with one that has knowledge of the type investments your interested in. Many of the best real estate investments, are sold by these agents well prior to MLS listing.