In the same vein as GL/LNC on Diablos, I'll throw my hat in for HBG with a shield mod. Guard 3 to 5 and shield = give 0 fucks about Diablos's bullshit. Piercing ammo is also crazy good on Diablos since it doesn't move tail that much and you're often right in its face. Legiana HBG is a good choice for Piercing.
Otherwise been largely IG-happy, I just pull out the HBG for Raths, Diablos, and Kirin because fuck dodging any of that.