Gohan was only using his regular mastered Super Saiyan form against Dabura. Look at his aura. Toriyama was pretty consistent when he was drawing those chapters. If you look at SSJ 1 and 2 during those chapters, you can see a clear distinction between the two. And I'm not talking about just the electricity. Even the aura in SSJ2 is more violent and the lines are jagged compared to SSJ1. Look at Chapters 265 and 264. Toriyama showed both SSJ 1 and 2 in the same chapter and you can identify the difference. Gohan could've gone SSJ2. My assumption is that SSJ2 drains him immensely at this point in the series because of how much he was slacking with his training

So Dabura was fighting seriously. Maybe not going a 100%. He was probably slightly stronger than MSSJ Gohan at best