Use both and build with arrows in 25 seconds.

demo with katana

it's really whoever is closest but if your pocket is on gunboats he might use up a lot of ammo building

escape plan. you get down to a certain health, and you pull out your escape plan and you build uber that way.

Generally scouts should be building, however in certain circumstances you'll want to pocket build with escape plan. Some times where it's preferential for pocket would be (not a complete list!):

• Highlander offclass defense with no scouts
  
• Enclosed, easily spamable areas where a scout building could easily be killed
  
• Expected sacks where you want both scouts to be healthy enough to deny bombers/etc.

Arrow building should also be built in to your team's plan as well, particularly at a moderate disadvantage (40%) or trying to build up a small advantage into a large one to push. We sometimes use demo to arrow build if he doesn't need to deny any areas, since both of our soldiers are gunboats.

on holds with disad you build with scout for sure so your soldiers can be forward spamming
escape plan building is generally done if you're the only person w/ the med while there's some downtime
your soldier can also arrow build w/ gunboats fairly effectively if he gets against a wall, crouches and shoots below himself, then shoots himself back at the ground off the wall. a bit better w/ cow mangler because ammo and all but yeah

generally in holding situations you'll wanna build with the scout over the soldier imo unless you're arrow building, more overall health and soldiers hold down chokey areas well and stuff

dont build run through chokes regardless of advantage get uber mid fight and surprise ur opponents by turning shiny outta nowhere

If pocket uses shotgun, build with him because :
-he'll have 260 hp if something funky happens and he can fight immediately
-he can build AND watch a door
-both scouts keep crit heals, full overheal, and can do other stuff if needed

If pocket runs gunboats either :
-build normally with one scout
-build with the enemy team (have your pocket sit in front of them and watch them waste ammo on him)
-arrow build with one scout

the reason you want to build with one scout is that your soldiers can keep crit heals and watch doors, whereas if soldier arrow builds, first it takes tons of ammo if soldier has gboats, and second he isn't watching his door anymore which opens a hole.

about holding chokes while building : your soldiers/demo need not peek to trade damage with enemies, because there is nothing to gain doing that and it fucks up the team's health/ crit heals status. If the team is building it's to be ready to fight once team gets uber. Being ready to fight means uber + full buffs on everyone.

pyro with backscratcher

If you're not trying to arrow build, scouts should always be #1 with the boston basher. If you happened to ever get bombed by a soldier, or someone runs at you, the scout immediately has the ability to shoot back at them. If you're using the Escape Plan, the soldier still has to deal with minicrits for a few seconds while he just put his escape plan away. Always remember that you scouts don't have to be super low to be building ubercharge with you.

Even if a pocket is running shotgun I wouldn't risk building with him because him consistently holding down a choke with 4 rockets is more valuable than 3 rockets. The 'optimal' way to be building with your pocket is if you want to tank him while he risks getting shot at multiple times. At the same time, he does put himself at the risk of dying and randomly being attacked by a sniper. Boston Basher building with scouts is much better because they control the amount of damage they're taking and they don't risk any random factors (like snipers).

If you are trying to Arrow Build, don't do it on a scout. In order for Arrow Building to be as overpowered as it is, you want to be constantly trying to hit your limit. The most amount of percentage you can get from an arrow is around ~10% (I was certain it's 9 but I'm probably wrong), and in order to receive that amount from arrows you have to do +150 Health back. Scouts have a max of 125 HP, and when arrow building with them, they can't risk going to absolute 1 or 0 health. So you only arrow scout for like 100 health at most, usually.

The most effective way my team found for arrow building is shooting arrows at a Demoman harming himself with a zatoichi from as far as you can. The Zatoichi does -50 health when you draw it back, so the demoman from full health can easily do -150 to himself. He can also still keep up his sticky traps.

Soldier running shotgun is probably the most optimal for arrow building, because he can be considered a throw away class as there are two of them. So if you happen to be rushed and the person arrow building dies, it wouldn't guarantee a point loss. If you're soldier isn't comfortable running around with a shotgun though, Demoman + Zatoichi method is much more consistent and doesn't risk someone playing out of their comfort zone of playstyle.

nursey very good medic man

Extra tip. A soldier with gunboats can build fairly efficiently by standing next to a wall. Jumping, pressing crouch after he is in the air, and shooting a rocket above himself on the wall. If done correctly the soldier will take crater damage and can easily keep up the amount of damage needed to build without risking taking minicrits/needing the med to take the beam off of him so he can get low enough to escape plan build. This is also useful for arrow building if you want to use a soldier to do it.

I thought the mexicans were supposed to build, thats what senor trump said atleast

useful but not optimal for soldier to do, you won't be arrow building at the maximum rate

scout is better i think ,because rocket spam is ideal to watch chokes then a scout.

and get 12k heals in a match 8)

.