So, this is an unnecessarily long and convoluted ramble, but worth a read, I suppose:
Termina's a good stage for this fight because you get to experience the strengths and weaknesses of each race firsthand in MM.
In terms of pure physicality, the gorons dominate-- like others have said, 6-8 feet tall edificial beings of stone tend to be pretty strong, as well as durable. They'd also be the most suited to mountainous terrain, as well as the cold, so seige wouldn't be much of an option to their enemies. However, they're not very technologically developed, and water may as well be toxic to them, as they can't swim, so any sea offensive is ruled out. Ultimately, they'd be unchallenged in the mountains and in the fields (rolling, anybody?) but would have difficulty expanding.
Of course, points go to those with a standing army-- those would be the Hylians, the Ikanians, and the Gerudo. The Gorons would also be able to mobilize pretty quickly, but not as smoothly; the Deku also seem to have soldiers, but let's be honest... Bubbles and spinning a soldier doesn't make, and there's also the whole fire issue, which Seth put pretty eloquently. They may have a marginal advantage in the swamps, due to territorial familiarity, but they'd be fighting a losing battle. On the other end of the spectrum, the zoras may have dominance in the sea, if they were militaristic-- but simply put, they aren't.
Of all the armies, the Ikanians are the fewest in number (we're not even sure if there are more then a few of them), though they do have a terrestrial advantage, as well as strong fortification. The Hylians probably have a fairly large and well organized army, or could raise one, and would very well be able to fortify and defend Clock Town, but would have trouble expanding into the mountains and swamp, as well as maintaining a hold on the fields against the Gorons.
They Hylians' main weakness would be resources. Clock Town isn't self-sufficient in the slightest-- it relies on resources coming in from the four other territories, plus the agricultural support from Milk Road. With the Gorons dominating the fields, Clock Town would be cut off from these territories and would suffer famine, disease, and technological faltering. Eventually, their military would be too weak to defend their holds.
On the contrary, the Gerudo enjoy all the same benefits of the Hylians-- fortification, organization, technological development-- not only to a greater degree, but also without suffering the downsides. The Pirates' Stronghold is practically impenetrable and their grasp on the sea would be challenged only, perhaps, by the Hylians, and then eventually by nobody when the Hylians declined. The Pirates would be situated in a strategically envious geographical position, especially with the bountiful sea to provide them with food.
Ultimately, it would come to a stalemate between the Gerudo and the Gorons, with the Gerudo unable to invade the fields or the mountains, and the Gorons unable to invade the sea or the swamps. I suppose, eventually, the Gorons, their forces less organized and more spread out throughout their larger territories, would decline due to internal disorganization, and the Gerudo would be able to more easily invade and conquer.
