I was wondering how much medicine is involved in the various surgical specialties. Do surgeons have the same medical capabilities as IM or its subspecialties?
No. Internal medicine doctors go through a 3 year residency and their subspecialists go through multi-year fellowships. A 5-7 year residency in general surgery is not mainly medicine plus a little bit of OR time.
Or do surgeons have the ability to practice basic medicine only?
What part of any sort of well-practiced medicine is 'basic'? And if one think it's basic, it's because one doesn't know enough to think of the other possibilities.
Under what circumstances would surgery have to consult any of the medicine specialties, or would they be able to handle it themselves?
Nephrology - dialysis for ESRD patients in for other things or ESRD patients with AVFs/dialysis lines.
Heme/Onc- chemo for the surg onc patients or the steroids and orphan drugs for the ITP
ID - weird infectious with resistant bugs typically in complicated ICU patients
Pulm - on board with the lung transplants.
GI - they do ERCPs, EUS for pancreatic cancer here and long-term medical management of Crohn's and UC.
Cardiology - sick patients can have MIs, too.
I guess the gist of what I'm asking is, are surgeons the most complete doctor's out there?
Baloney. There is no 'super-human all-knowing doctor' who can practice everything from Neurosurgery to Rheumatology as they do on the TeeVee. All competent doctors are 'complete' doctors in their respective fields. That being said, some doctors know relatively less depth about a lot of topics (generalists), and some doctors know a greater depth about a fewer number of topics (sub-specialists).
General surgeons know how to practice general surgery which includes peri-operative medical management for a wide variety of conditions, but they are not whom you want to see as your PCP.
And if not, what other specialties would be considered some of the "best doctor's" out there, in terms of overall capabilities surgical or medical.
There is no 'best specialty' out there in terms of overall capability. There are generalists and specialists and each scoff at the other's breadth and depth of knowledge.