This is a guide on how to set up the game for mods, play online and set up the game to let you switch them on and off.
In order for the game to launch with extra files, you need the patcher made by Eternity. The DLL file it provides makes the game load loose files from the data folder in your game directory over the actual game files in the CPK archives. The patcher is always available from the animegamemods website from this thread: http://animegamemods.net/thread/4059/tools-eternity , although to access the download link from there, you need an account. Here is the link to mega for patcher version 3.3, although you need to make sure it hasn't been updated and that the link here isn't outdated.
Once you have downloaded the patcher, you need to unpack it in your game directory, over at the steam library or steam directory of your choice, steamapps\common\DB Xenoverse 2. You can also find this folder by going to steam library, properties of the game and viewing local files. You want to put the two folders from the patcher archive into this folder, and merge the bin file.
Now, at this point the game won't work, you need to do either of the two things: disable EAC by renaming/moving EAC files from the game directory, or disabling EAC check.
Go to the EasyAntiCheat folder in Xenoverse 2 directory, and rename the file EasyAntiCheat_x64.dll, the easiest way is to remove one l at the end. Now to run the game, you need to use the DBXV2.exe in the bin file in Xenoverse 2 directory (if you try to run it from steam, EAC will still detect the patcher's dll file and stop you from booting the game), so make a shortcut to it for convenience. When running the game this way, the game will tell you you have booted it without Easy Anti Cheat, and force you to stay offline.
If you want to disable your mods to play offline again, do the renaming trick to the dll file of the patcher instead, renaming it to xinput1_3.dl, and renaming the EAC file back to its original form. After you do this, you'll be able to run the game from steam again, but without any mods.
Disable EAC check (play with mods online)
XV2Patcher actually has an option to allow you to play with mods without EAC preventing you from entering into online lobby. You have to go into XV2PATCHER folder in your game directory, and edit xv2patcher.ini file in any text editing file. Scroll over to the patches section, and at the end of it you'll find an option: "excessive_air_contamination", which you need to set to true. Now you can let the EasyAntiCheat file alone, but you'll still need to boot the game from its exe file in the bin folder.
In order to easily switch between having the mods activated and deactivated, duplicate your bin folder in Xenoverse 2 directory, and remove the xinput1_3.dll from the old one. Make a shortcut to the DBXV2.exe in the other bin folder (which you can name to something like bin2). If you want to play with mods, use the shortcut to the exe. If you want to play without mods, start the game from Steam, or use the exe in the original bin folder.
note: Xenoverse 2 Mod Installer requires the xinput1_3.dll file to be in the original bin folder to work, if you want to use it, you'll have to move the dll back, but afterwards you can move it back.
Although booting the game with excessive_air_contamination patch allows you go into online mode and multi lobby with the patcher active, EasyAntiCheat does verify player's checks whenever they try to play together, meaning that you cannot play with people who do not have the patcher active, if you attempt to do so, you'll be kicked from the room with communicate: "You have been removed from the session by EAC".
When playing against people who also have mods, care must be taken with certain custom elements. While cosmetic replacers will work fine, custom x2m characters, custom skills and modded movesets will require both players to have the mods installed. Additionally, care must be taken when modifying the roster, installing a character in a different place and shifting the roster can lead to serious glitches in play, with characters appearing as someone else. Other glitches include infinite loading screens or just crashing the game.
The easiest way to ensure compatibility, is for one player to prepare the modded data folder, and send it to the other player. They can then add their own mods on top and still play with the shared modded content between them.