According to WG, Sommers and Gaban knew each other from God Valley, and in the chapter were Sommers got his hand cut and couldn't regen, Sommers was shocked that Gaban could hurt him.
This implies that Gaban most likely learned how to bypass the regen at Laugh Tale.
And only the Roger Pirates went there, so again none of the Yonko's would know how to permanently hurt the Elders and the Holy Knights.