I suppose a digital watch could have just the first two...
Only if the watch has a LCD screen and there are no hands. When analog hands are used there must be a motor to move the seconds hand.
but anything with 1 must have 2 and vice-versa .
Not necessarily, Seiko's proprietary SpringDrive movements don't have a battery. The electricity is generated by a small generator. The generator itself is powered by kinetic energy stored in a spring.
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