I have an idea on how to do it, but i'm not sure if it work. Anyway:
Look into gamemodes/sandbox/gamemode/init.lua, just to see how to give weapons and ammos. Then in /garrysmod/addons/ulx/lua/ulx/utils.lua, make a function that give certain weapons to a certain team, then add a hook to PlayerSpawn.
It should be good to have this option in uteam or something. I could try to add that for uteam, but i'm tired now, 03:08. Or maybe there is already a way to do that?