''even if he has it''
Previously was saying he didn't have it, now we are getting there troll.
That would be saying like Big Mom's CoC sucks because she has natural super durability + DF power. Teach could use 2 DF powers, why he shouldn't try it when he could use all abilities.
Yamato uses CoC as well as Zolo while attacking, that doesn't make them anywhere near close to Yonko level, there are levels to that.
Of course DFless Teach can use it, thats how he scarred Shanks.
Teach would be a Yonko without it, but except for low-diffing WB Pirates, he would high-diff them. Teach didn't want to make it a close fight.