Auto-GI looks like it might be a 4A+B. Low could be a 1B
Everything out of his SC appears to be a Brave Edge-style follow up.
There was a video I saw where it appeared Groh had a GB-low attack. Not sure if it was out of his DB stance.
From DB, it looks like DB A goes into the attack throw animation with that flurry of slashes. You can see it once in vs. Mitsu and once in vs. Night.
Note that 3B and another launcher have similar animations, but one of them, actually has Groh step back and hold a charge first. In another video you could see him do this without have SC active.
General Impressions:
So it looks like we have a beginner friendly new hero who may or may not be the star this game, or at least an outside observer. Everything I've seen so far indicates that he's very beginner friendly and has a number of lengthy vertical and horizontal string attacks, but no real iconic punishers. This makes me think of him as a character that's very similar to Kilik and Xianghua with a very beginner friendly mindset that has some open possibilities to more complex options (ie, AD, Festival). In this case, his dual-blade stance may not be the only option he has.
Perhaps ironically, he bears a range that appears shorter than Xianghua's and Kilik's, despite wielding a two-handed weapon. His fighting style, gives him the appearance of a more agility-centric hero than a middle-ranged hero like Kilik, Nightmare, Mitsurugi or Raphael. His damage is decent, but not remarkably high for his perceived weapon class, and it seems like he'd fit in with more speedier heroes like Taki.
That said, we haven't seen everything of him yet, but I am a little worried. He doesn't appear to have any real counter-hit stuns, forced crouches, massive block stun, or truly threating punishers. His theming seems very much like a character who overwhelms his opponent with multiple hits and attacks at close range and at various heights.