There are two general ideas. Long/midrange or brawl.
The longrange and midrange builds are usually equipped assymmetric as you are crippled alot on closeranges and usually have the time to switch sides.
This loadouts have their closerange on the left with a hwacha carronade and a long to midrange side left.
merc, lj, hflak is the standard longrange loadout. Dual lumberjack hades is more disable oriented. lj hwacha hades is midrange and isnt very effective above 1200m but is when the enemy gets closer and gives you saver fights when the enemy gets close due to the disable ability.
Brawl builds are different. Some fly symmetric brawl galleons as the galleon isnt the fastest ship and also turns quite slow so they dont want to face the inability to fight on one side and dont want to get outmaneuvered. Others fly it assymmetric with either lj, hflak but i prefer dual lumber as a hflak is kinda ineffective without a decent piercing weapon.
If u however fly it symmetric i always suggest using the hwacha carro aswell on the right side. hwacha hwacha lacks alot as it cant kill effective due to long reload and the second hwacha doesnt give alot when the enemy took the first hwacha which already disabled him.
The left side on a brawl galleon is often dual hwacha + gat. In this comb the second hwacha is used to finish off the enemy after the first hwacha disabled the enemy and the gat shred the armor.
But those closerange sides are so different that you cant name them all. Most combinations of a closerange topdeck gun and a combination of carronades and hwachas. Usual idea is. The more your focus is on the hwacha on the lowerdeck the harder you want a piercing gun to shred armor. The more you focus on the carronade the more you want a explosive or disable gun.
A galleon, especially the longrange one, is a sitting fortress. You want to move as little as possible to make the aiming of your gunners as easy as possible. Get in a good position and shoot the enemy out of the skies.
Similiar thing goes for the brawl galleons. Get in range and arc and kill them. Dont go for fancy maneuver or dodges on your enemys. You are a slow and immobile fortress. You get in arc and kill. You can also take alot of a beating. However a good team will know that and wants to outmaneuver you. Use the tools (phoenix claw is a must) you got to counter this. Grab your correct altitude and dont let the enemy get away. Your slow. You dont want to run after the enemy. You also dont want to run away. A running galleon is a not shooting galleon which leads to a dead galleon.
Another tip: as pilot you can jump down to the hull when under pressure and help rebuilding it. You can also rebuild the balloon quite easy as pilot. As long as you got your guns in arc this is most times a nobrainer. Let your lower deck shoot the enemy from the skies and help your main engineer on the upper deck to stay alive.