I have found a good controller, it is a controller from Trust and it is called Trust GXT Nomad. It works when I plug it into my computer, but when I plug it into my Xbox 360 it does not work, even though it has xInput. Any ideas why it isn't working when it should be? Thanks!
XInput and Xbox 360 Compatibility are two different things.
Any controller can be made XInput compatible on Windows either in Software (eg. the DS4Windows program for an XInput DualShock 4) or Hardware (flashing a different firmware or a physical switch), but they need to be specifically tested on an Xbox 360 due to the console checking for the device information and refusing to connect if it doesn't matches.
The Trust page for the GXT Nomad never mentions Xbox 360 compatibility because it was not designed and/or tested for it: