FFX - Capture Barbatos

[Orangatuan]

I have collected 10 of every monster except Barbatos, I have spent nearly 10 hours farming sin and I have only seen 4 barbatos.
Is there a spawn requirement that I'm missing?
Does anyone know of an INGAME method of getting more to spawn? i.e. no editors.

[Orangatuan]

And while I'm asking questions. The complete the sphere grid achievement, everywhere I've looked seems to be rather lacking in details on this.

Does it mean just visit every node?
Does it mean just activate every node with something in it?
Do I need to fill all the emptys?
Is activating every node enough or do you need to visit every path?

[Casurin]

Barbatos can be found in the later half of Sin with a decent encounter-rate even.

The achievment - activate every node. So yes, you need to fill everything.