the first item is to integrate Iridar's EW MEC Particle Projection Cannon as the Improved Plasma tier, The Mercenary MEC Cannon, and the Spark arsenal's coil and laser spark rifles to have them integrated into the 9-tier phoenix point like system

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1626184587
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2127166233
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3042712139&searchtext=mercenarys+plasma
(And also maybe have the Mechtoid's gun act as the Plasma or Improved plasma Heavy cannon? I haven't checked it's firing animation)
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2976640015&searchtext=mechtoid

Mercenary Plasma Ghost Templates won't be happening :) Those are used as cosmetics for the ABBA improved Laser Weapons

so it's already implemented? :3

If you use ABBA yes ... you will see them :)

not sure if these are already worked into 9-tier or ABBA but-
what about item's like the gatling rifle, GOC's weapons, maybe some of SCP's guns?
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1505294997&searchtext=viper
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1930344321&searchtext=goc
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1774066942&searchtext=SCP

also for some Frost stuff
Frost Legion (the weapons that they drop)
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2481645156
Bitterfrost Protocol (mostly the Viper king ripjack)
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1891339003

another is the Chimera squad guns
the Frost legion also uses :P
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2556737873&searchtext=chimera
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2588148308&searchtext=chimera
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2588160776&searchtext=chimera
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2601581428&searchtext=chimera
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2623147658&searchtext=chimera

Maybe something to implement?
(like Res. firearms & World War weapons to Call of Duty: Infinite Warfare?)
the shotgun from infinite warfare is a Sonic weapon!
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1132835147&searchtext=resistance
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2471449861&searchtext=bayonet
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1816536981&searchtext=world+war
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1695261557&searchtext=infinite+warfare
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1637515824&searchtext=grenade+launcher

I think another might be the Requiem For man Armory
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3010467224&searchtext=