The Baghdad Battery was not used for electroplating, but Mythbusters has convincingly shown that it could have been: ten similar copper-iron cells with lemon-juice electrolyte produced a total of four volts and successfully electroplated a token.
I wonder if particular applications of electrochemistry were actually used but not understood. For example, in, I think, Huckleberry Finn, which is full of folk beliefs about such things, a character is at one point faced with the problem of what to do about a counterfeit quarter, which had worn and was showing the copper around the edge. So they put the coin inside a baked potato overnight, which restores the silver appearance to the edge. Huckleberry Finn was published in 1884 but purports to describe the beliefs and folkways of people in Mark Twain’s childhood around 1840.
Silver’s standard electrode potential is +0.7996 V, while copper’s is +0.520 V. Alkali metals and alkaline earth metals, which are the most enthusiastic about giving up their electrons, have among the most negative standard electrode potential, so this means that, in a copper-silver circuit, copper has a slight potential to give up electrons to the electrolyte and oxidize, dissolving copper cations into the potato, while silver would tend to acquire electrons from solution and be reduced. This calculation is confirmed by the existence of the “red plague”: partly-silver-plated copper conductors exposed to moisture form red cuprous oxide through galvanic corrosion, rather than the silver anodically protecting the copper. This is unfortunately the reverse of the mass flow direction that would be required for the counterfeit-quarter trick to work.
The other metals known to the ancients were lead (-0.126 V), gold (+1.52 V, but I think not actually usable), iron (-0.44 V), tin (-0.13 V), mercury (+0.85 V), and, in India, zinc (-0.7618 V, or -1.199 V as zincate). Among other significant battery electrode materials, carbon (whose electrode potentials are, I think, irrelevant) and air (oxygen? +0.401 V?) were also known. Although the insulators litharge and minium were known, lead dioxide was not.
(In modern lead-acid batteries, the lead dioxide is formed electrolytically by the sulfate electrolyte, but of course this requires an external voltage source.)
Of these the champions on the positive side are mercury and silver, while the champions on the negative side are iron and zinc. This suggests the possibility of constructing a battery with some 1.8 volts per cell, almost the same as modern batteries, out of ancient metals, or something like a lead-acid battery, but using a different electrolyte, out of ancient materials. It would probably be more practical, though, to use plentiful copper, rather than precious mercury and silver, despite the rather miserable voltages available.
Above I said I didn’t think gold would work, thinking it would be too inert to interact with electrolytes. But gold here wouldn’t be the electrode that would need to dissolve, so Bernd Jendrissek tried some gold-plated copper contacts along the edge of an old SIMM with a paper towel soaked with salty vinegar and a copper wire on the other side of the paper towel, getting 0.3 V and a few microamps. So, if Jendrissek’s report is correct, it seems that gold does work.