How to enable routing in OS X El Capitan
Your router is not responsible to route packets from 192.168.0.0 to 192.168.56.0, but the VM host is. You have to keep the static route 192.168.56.0    -> 192.168.0.2 on the router though. I don't know what's the purpose of the second route 192.168.57.0 -> 192.168.0.2 - probably a second NAT adapter on the  host.

To reach your VM from other OS X devices in your 192.168.0.0 network you have to set up a static route on each of the 192.168.0.x machines to the VM host:

sudo route add -net 192.168.56.0  192.168.0.2


To make this route persistent add a launch daemon on each of the machines:

sudo nano /Library/LaunchDaemons/local.staticroute.vm.plist


with the content

&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"&gt;
&lt;plist version="1.0"&gt;
&lt;dict&gt;
    &lt;key&gt;Label&lt;/key&gt;
    &lt;string&gt;local.staticroute.vm&lt;/string&gt;
    &lt;key&gt;ProgramArguments&lt;/key&gt;
    &lt;array&gt;
      &lt;string&gt;route&lt;/string&gt;
      &lt;string&gt;add&lt;/string&gt;
      &lt;string&gt;-net&lt;/string&gt;
      &lt;string&gt;192.168.56.0&lt;/string&gt;
      &lt;string&gt;192.168.0.2&lt;/string&gt;
    &lt;/array&gt;
    &lt;key&gt;RunAtLoad&lt;/key&gt;
    &lt;true/&gt;
  &lt;/dict&gt;
&lt;/plist&gt;


save the file (ctrl-O) and quit nano (ctrl-X).

Load the launch daemon with:

sudo launchctl load -w /Library/LaunchDaemons/local.staticroute.vm.plist




If the other devices in the 192.168.0.0 network are Linux/Windows/Android hosts use the respective commands to add a route:

Windows (persistent): 

route add -p 192.168.56.0 mask 255.255.255.0 192.168.0.2 


Linux:

route add -net 192.168.56.0 netmask 255.255.255.0 gw 192.168.0.2


To add a persistent route in Linux check your Linux distro documentation.