I am not too sure to get the question. Please let me try to answer anyways. A new particle is new by definition. The properties of this new particle can be very varied. It could be sensitive to the strong interaction, the weak interaction, etc. This will fix the way particles can be produced (via strong or weak forces, etc.).

To answer the second part of the question, new particles can be light. One just must be sure they are stealthy enough to guarantee the fact that we have not observed them yet.

I hope this helps.