Dave Smith Instruments SYNTHESIZERS

So I'm using the desktop Evolver as an effects unit and loving what it
does but I notice there are specific effects for guitar and bass
(Banks 2 20-40)-and then some aren't but sometimes they will still
gate the effect. Obviously you can set the Trigger Select but so far
it doesn't seem that all the effect that react to the sounds are
dependent upon that.

So my question is:

What defines how the Evolver responds to sound?  What makes a sound
more viable as a effect as opposed to just a synth.  Is there a way to
alter a  sound so its gates the way the sounds in bank 2 do?

Thanks in advance!

J