My question is do fighters have to select brawling group at lvl 5,13 to increase their unarmed attack profiency? ( Fist headbutt
Claw)
Core rulebook (4th printing):
Choose one weapon group. Your proficiency rank increases to master with the simple weapons, martial weapons, and unarmed attacks in that group, and to expert with the advanced weapons in that group. You gain access to the critical specialization effects of all weapons and unarmed attacks for which you have master proficiency.
Core rulebook errata:
Any class feature that improves the proficiency rank or grants the critical specialization effect access for simple weapons or a specific set of weapons, that ability also grants that benefit for unarmed attacks.