Kyros is just the first guy from the start of the NW, there are many other as strong and stronger in the NW in nations under the WG, the point is at best the yonkou would be 200 000 strong while the WG would be 1billion strong at least there is just no wining against that, sure majority would be useless but so would the majority of the pirates so it evens out, until we come to the point that the WG just has more people stronger, Shanks has about 10 top fighters, Teach about 10, Big mom and Kaido probably about the same and out of that 40 most are VA level, while the WG has much more stronger people, not to forget unknowns like Fujitora and Greenbull, it is just to much for anyone that is why the RA are turning countries against the WG because they wouldn't win any other way
look at this for example :
Mihawk vs Shanks
Fujitora vs Kaido
Greenbull vs BB
Kizaru vs Bigmum
leaving out people like Akainu and Kong who a both admiral lvl who can make it 2 vs 1 scenario if one of their own is losing, do you see my point, the WG at full strength is way stronger.
not the marines but the WG, they pretty much control the world and who lives and who dies, they wanted Whitebeard dead and they used Ace to get to him, they don't see Shanks as a thread to them so they let him roam, but any time they would want any of them dead they can do so
Kyros is just one case and even then he was the sole strong guy in the entire country. Dressrosa was originally a supposedly peaceful nation but still, considering they were at the NW it does not set a good precedent.
Its not the case at all that the majority of pirates would be useless. You are comparing pirates that at least have been sailing through the new world against military which normally just stays in a country. Sure, each crew has around 10 crewmembers who by all intents and purposes make up the main crew but that does not mean the rest of the people there are just normal folk. just look at shanks crew. Remember shank's delivery guy? Rockstar was a pirate with a 94 mil bounty before he joined shank's crew. Basically a guy with a bounty 6 mil below a supernova is a delivery boy in a yonko crew. So with each yonko you have the main crew which is made up by around 10 crewmembers whose strength is comparable to admirals and vice admirals and then you have the rest of the crew which is still made up of guys with significant bounties. And then even after that you have the allied crews of each yonko which is made up of pirates of varying strengths.
Remember the strawhats vs hody's crew? Each fishman by default is several times stronger than a regular human and even then the strawhats, who are not even remotely close to the strength of a yonko, had an easy time with them. Luffy took out 50000 people. The rest of the 50000 people were easily dealt with by the rest of the crew. Even nami, ussop and chopper were not phased by the numbers. According to oda shanks would have taken all 100000 fishmen with his haki to boot. Now, what would be the result of putting the sheer numbers you mention against the yonko? The yonko would take care of most of them through literally sheer willpower. Even against WB the WG only took its elite marines and even then a number of people were susceptible to luffy's haki.
Just throwing numbers out there would accomplish nothing. Gather the billion people you mention and they would probably be handled easily by the yonko's fodder members. Even pre time skip luffy could rampage through the great war defeating regular marines and his strength was by all intents and purposes negligible. The war would be decided by who has the most quality warriors, not simply who has the most warriors. And in this regard the yonko have the marines beat. To begin with nation independent armies are not a thing, they weren't even present during the previous war. So the situation would be more along the lines of this assuming the world government takes everything it has without leaving anything to protect the rest of the world:
Marines:
- Fleet commander
-3 admirals
- (15-20) Vice admirals
- Elite marines
-Militia
-pacifista
-7 shichibukai
That is pretty much what made up the WG's army at the great war. And within this you have to consider that by far the vast majority of the WGs power was concentrated within about 20 people. Basically the fleet commander, the 3 admirals, and the 15 or so vice admirals. Pacifista are strong but moderately strong people can one shot them (basically any Vice admiral and up). And then the shichibukai although they are too erratic to really be considered an asset. I mean, hancock was uncooperative, mihawk and doflamingo just did as they pleased, BB only showed up to do his thing....
And now you have the 4 yonko:
- 4 yonko
- about 40 relevant crewmembers for each crew (made up of people with Vice admiral and admiral level).
-Allied crews (with each having a relatively strong captain and perhaps competent crewmembers). WB had 43 of this IIRC. If the yonko now have something similar we are talking about 160 crews.
- Their regular members (however many rockstars they have between the yonko crews and allies)
-Militia
The WG could gather the billion people you mention and they would still be severely outnumbered by the sheer number of strong people on the other side.
