Penetrating DR / Good

[Atalius]

What are some ways to help my martial companions get through DR Good with there piercing weapons?

[Drejk]

Align weapon spell (Clr 2) is the primary way. It could be made into an oil to smear on weapons. Another way is having a +4 enhancement bonus on weapon, which passes both cold iron/silver, and alignment-based damage reduction, or having holy weapon property.

The simplest solution, though, is simply stack as many damage bonuses as possible and suck up the damage loss caused by reduction.

[Shorticus]

Or purchase oils of Bless Weapon, a paladin first level spell.

[Pink Dragon]

Be a bloodrager with the Celestial bloodline.
Have a +5 weapon (+4 only gets past material-based DR).
Use arrows and the clustered shot feat.