Here's my Fight Prediction. But let me start with this.
Since Gildarts' ass is somewhere that he's not really THAT useful for the guild. We won't see him in this arc. During the Tenrou arc, after his fight with Natsu, he immediately traveled back home, and then returned. Why he returned? Because if Gildarts didn't return, then, he wouldn't be frozen for 7 years, and that means, Fairy Tail won't be so down for the past 7 years, since Gildarts is with them.
And now to the fights:
There might, or might not have a guild alliance. So let's assume Lamia, Saber and Pegasus or Mermaid. Will be participating in this arc.
9 Gates Strongest 3 Members
Obviously, Silver vs Gray. or (if there would really be an alliance, Gray and Lyon vs Silver)
One of the 3 strongest vs Laxus and Natsu
One of the 3 strongest vs Jura, Toby and Yuuka
I doubt Kyoka is one of the Top 3.. so.
Kyoka vs Erza and Mira (Hell Yeah! this would be awesome)
9 Gates Member 5 vs Rogue and Gajeel
9 Gates Member 6 vs Sting and Kagura
9 Gates Weakest 3
9 Gates Member 7 vs Chelia, Orga, Rufus and Wendy
9 Gates Member 8 vs Juvia, The Trimens and Milliana
9 Gates Member 9 vs Lucy and Yukino. This 9 gate member will be the biggest Pervert in Manga history.
For the Guild Master?
Warrod is actually a fighter! and will be fighting the Tartaros Guild Master, which would kill Warrod, and then Natsu, Gray and Erza will be fighting this Guild Master to take revenge on killing Warrod. With the death of a Wizard Saint, another addition to the group will be needed. And Laxus will be taking the seat, once the arc ends.
Non-Demon Gates Tartarus Members and Minor Dark Guilds Shadow gear, Raijinshuu, Lisanna, Quatro Cerberus, rest of the Mermaids, will be facing the Minor Dark Guilds under Tartarus and the weaker Tartarus members.
I wouldn't be surprised if we get to see Phantom Lord's Element 3 in this arc.