Well, Ope Ope's probably the second strongest Paramecia and its awakening was legit matched by a basic GGnM move. It's clearly the strongest Paramecia by a landslide.
I don't believe BB even use Tremor DF there unless Oda changed the design and forgot to add the classic Tremor DF sound effect, its more like just BB's Haki or could be Ad.CoA (or Ad.CoC).
And why would Oda make BB's hand armament black if he wanted to focus on Tremor DF? We see BB wasn't using armament with Tremor DF before.
1- This is how Tremor DF bubble looks like:
This is the sound effect of Tremor DF: WMMM
Tremor DF bubble has black marks around, and completely white inside, not gray.
It usually has WMM or Krak, Kaboom etc sound effects when its used, there is none of those voices here in this clash.
And it has only a sound effect that's used for CoA Haki, which is GACHING.
The bubble design looks more like Law's room, it doesn't look like Tremor DF bubble.
Law's room design, white color in the center, no black marks around it, and gray tones inside.