Guild vs. Guild
Oh see they got rid of this from GW 1 when it was the only thing that kept the game alive for so long -.-, they removed it to be more like WoW and completely ruined it for that group of people. They wanted to make it more PvE noob oriented
That would be a community thing, it will get hosted trough gw2-pvp.com however it is still in development.
GvG is a 8v8 GW1 PvP gamemode.
What you are doing in OS is just a braindead zerg clash and it’s as far from competitive as it can get.