😂
Heihachi will get manhandled by anyone in possession of the Devil Gene. Still don't think he beat Devil due to major PIS Nikk? Why is Heihachi then scared shitless of the Devil Gene in T4? Yup...
One probable cause is that Kazuya was in a mind conflict due to Devil and Angel's fight over his soul, and if you still think Heihachi > Devil as of T2, as of T4 he got laid out literally by a small fraction of Devil's power.