How can you tell the difference between v-fib or v-tach and asystole or pea with no electrical equipment? basically, shockable vs nonshockable.

You don't: Thats why defibrillator systems have the ekg built in or are built to automatically analyse the rhythm before recommending a shock.

No.: To tell the difference you will need an ekg machine or something that can take a telemetry strip (like an aed-automatic external defibrillator). On exam all of these can present with weak or no pulse and low or no blood pressure.

See ACLS: Number one you will not shock on your own unless you are trained. But basics wise, all of the above in all likelihood the person has a sudden death, and has no pulse or BP obtainable except may be early and slower v-tach. Again qualified personnels are the ones who would administer shocks. If someone needs a defib, an implantable one should have been placed.