[Android Q&A, Help & Troubleshooting] ThomasKKKK:
I solved it!

!!! I SOLVED THE PROBLEM AND MADE MY GALAXY NOTE 5 NATIVELY SUPPORT XBOX360 WIRELESS CONTROLLER !!!

(S6 & S6 EDGE & S6 EDGE PLUS INCLUDED & AND BY NATIVE I MEAN WITHOUT ANY KEYMAPPING APPS LIKE USB/BT)

And now to everyone who has a Samsung Galaxy Note 5 and have problems connecting Xbox 360 USB or Wireless controller, i would like to share my solution, just to save time for some people with a similar problem.

If you have an older device, it's easy and there are many tutorials out there, but for people like me that have a newer Samsung's smartphone like Note 5, S6/edge/active etc. there is one thing you need to know - these devices no longer have native support for wireless xbox360 controller. After hours of searching, testing keymapping applications, editing system's key input files, creating and exploring them, i tried to install xbox360 driver module by myself, but my system (through Terminal Emulator) would not let me do that. After all that "trying" to make it work and some more googling i found out that the problem actually is not here. The real problem is the Kernel. The Kernel is the thing that controls everything on your device. So, i spent a couple of minutes searching for a Kernel that has full xbox 360 support and i came up with arter97's Kernel (I will post links in the end). A fact worth mentioning is that i have a Note7 Port ROM installed on my Note5 and that was where i made a mistake, i soft bricked my Note7. Before i've been using Minotaurus V10 custom ROM and Infinity v1.0 Kernel. Important info: I updated only my Kernel and left ROM, my data and apps untouched. At the first try i downloaded arte97's Kernel for the Note5 (n920cig) and soft-bricked the phone, i let it boot up, but that took ~35mins and was still loading, i couldn't turn off my phone (solution: there was samsung logo on the screen flashing and power button didn't work > i was able to enter download mode > select "No" which leads to reboot my phone > from there enter recovery and restore backup i've created before using TWRP recovery - that's how you un-soft-brick your phone). After this accident i found that the arte97 has a specific Kernel edition for galaxy Note5 that has Note7 Port rom installed, which was my case, so i gave it another shot, downloaded the Kernel (-N7/Grace UI Port'ed edition for N5) and the first boot-up took around 2-3minutes. The device works just like before switching Kernels, fast and smooth. Time to test the xbox360 controller - BOOM! it connects instantly allowing me to interact with the screen (using microsoft xbox360 wireless controller & official microsoft xbox360 USB receiver). I open up the game (Riptide GP2) and everything works without any adjustments, i checked the controls, the game automatically shows the image of a x360 controller. I also had "Dead Trigger 2" installed - same story, i can assign any button to do any action in the game. I've finally achieved what i was trying to do!

Here are the links i've been using:

My OS: https://xdaforums.com/note5/development/rom-minotaurusrom-v1-note7-port-t3461731

Arter97's Kernel with native xbox360 controller support (I upgraded my Note5 to the v22.0 version):

XDA-Developers page: https://xdaforums.com/note5/development/arter97-kernel-galaxy-note-5-t3189907

Official page (there is a link to this page in the xda page): arter97's Android studio

I have also have had these files installed on my phone before changing kernels (Vendor_045e_Product_0291 = wired x360 controller, Product_0719 = wireless, so i've created a .kl file with number 0719 and i downloaded a key character mapping file for x360 wireless, which ends with .kcm):

https://xdaforums.com/showthread.php?p=29232978#post29232978

Before changing Kernels i made it work using USB/BT app. All the buttons were working using an older version of USB/BT, but the problem was that it was not comfortable enough for me (having to change keyboard every time & stick directions are registered as buttons, so in first person shooting games you can't aim slowly, it always goes at the same fast speed). If you are like me and want to use xbox360 wireless controller like "plug and play", you gotta check this thing with Kernels (^^), if you don't want to risk and think the emulator will be OK, i will leave a link to a USB/BT Joystick center tutorial bellow. (The guy in the video is using Galaxy S6 active, but my Note 5 also worked, so any other S6 will work)

https://youtu.be/I9fvLZMd9bE

Hope this helps!