I support putting story and motivations behind this. Take the battleground into account. We can't assume that the Zoras will always be near water, or the Twili have all the power they had in TP.
- Hylians
- Shiekah
- Gorons
- Zora
- Deku
- Twili
- Kokiri
- Ikanians
- Ooca
- Gerudo
So, let's start with where everyone's coming from. We'll use OoT-era, since the only races that don't appear in OoT - the Twili and the Ooca - probably existed during OoT time and were simply... unavailable. This is simply for the simplicity of preparing the battle.
Hylians: Ocarina of Time Castle Town
Shiekah: Ocarina of Time Kakoriko Village
Gorons: Ocarina of Time Death Mountain
Zora: Ocarina of Time Zora's Domain
Deku: Majora's Mask Woodfall
Twili: Ocarina of Time Twili Realm
Kokiri: Ocarina of Time Kokiri Village
Ikanians: Majora's Mask Ikana Valley
Ooca: Ocarina of Time City in the Sky
Gerudo: Ocarina of Time Gerudo Desert
We'll say this takes place in the child timeline, due to the inclusion of the MM races. Let's say about a decade after OoT and MM. Link and Ganondorf will be null factors here, since they're both massively OP.
The war would probably begin with a Twili invasion. Not led by Zant, but someone similar who wants to return the Twili realm to its former glory. I'm going to say that the events of OoT and MM weakened the barriers between worlds and allowed them through. They'd immediately go for the obvious seat of power - Castle Town.
Here's where we'd have to think about the Twili and their power without Ganondorf, as we discussed above. I think that Deus has a point with that Ganondorf quote - most of what they did came from him. So let's just say we have an army of Zants with some base magic, but nothing overly strong. The Hylians would actually stand a chance, but I feel the Twili would still win. They would remain in Castle Town to lick their wounds while the Hylian survivors would go to their allies - the Gorons, the Zora, the Kokiri, and, most importantly, the Shiekah. They would probably send out warriors to fight the Twili. The Kokiri, not being very capable fighters, would act as medics. The gorons would be tanks, going in front, and the zora as support troops. The Shiekah would sneak inside and be ninjas while the armies were distracted. It's a pretty even fight with the gorons and zoras. However, the Shiekah turn the tide of battle, sneaking inside and killing most of the Twili, returning the Hylians to power. Some of the Twili would escape, and seek solace with the enemies of the Hylians: the Gerudo. The Gerudo, eager to avenge the imprisonment of their king a decade before, would be more than willing, but would do so quietly, because they feel like an army of all the other races would be too much to handle. They agree to take out the other races one at a time, quietly. They start with the Kokiri, who don't put up much of a fight and fall to a small taskforce. Next, they'd go for the Zora whil they have scouts explore the lost woods. As we've seen from MM, the Gerudo can even beat the Zora on their home turf, and, with the aid of the Twili, own them. They don't annhialate them, but they do beat them into submission.
The Gerudo are getting wary at this point, but the other races are realizing what's happening at this point. They need to act quickly. The Gerudo scouts find the entrance the the Goron Village in the Lost Woods and decide to make the most of it. They go in and attack the Gorons. However, their armies are weakened from the previous fights, and they end up being beaten mostly, since the Gerudo kinda have spears and the Twili are severely weakened.
That's where I'll end it for now. There's more to come for sure, but the Ooca, Deku, Ikanians, and other race wars are hard for me to set up as of now. Thoughts for what I have so far?