Seeing as FE7 and FE8 (and also FE5) already have PvP Hacks (where you gain control of the Enemy Army), yet FE6 doesnt, i tried finding anyone who has created a PvP Hack for FE6.
While i couldnt find a patch for FE6 PvP, i DID find a tutorial by Kemui52 (Tutorial) on how to make it yourself and asked for permission to post a Patch for this
So here is the Download for FE6 PvP!
Dropbox
The Patch lets you control Enemy and Ally Units.
All Fog of War is removed so it works properly on those maps.
All Gaiden Requirements are removed, since most of those would be impossible to achieve in a PvP setting.
The requirement for True Ending Maps is the same though, so dont lose any Legendary Weapons.
Apply to JP FE6 ROM
Also note that Recruiting Clarine is a bit bugged. You need to recruit Rutger with Green Clarine and then Talk to Roy. She disappears upon being Recruited and should reappear in Chapter 5.