Well. Since E17 is in the making, and im too impatient, i wanted to do this. This is for fun, there are nearly to no spoilers, i think...
As we may already know, Tania is the next Gym. Why? for those who still dont know here are the "why":
Well, Now Tania. Until Now we have only seen two Pokes of Tania's Team. Excadrill and her Ace Aegislash.
I think she will have either a Klefki or a Mawile, since Tania comes from Titania, and Titania is the queen of fairies (but i think Tania is inspired in an anime character Erza Scarlet aka Titania from Fairy Tail, A swordfighter with plenty of armours. Ame, however, said (and this frustrates her) that its not based on Erza, its just waaaaay too much coincidence). I think Mawile, since Klefki isnt much of Tania's Personality.
I also think she'll have a Metagross and/or a Steelix OR and Aggron. Its most probably that Steelix or Aggron will be megas, since a Mega-Metagross seems too dificult, even for Ame. Metagross is likely to be in her team, to keep controled the fight-types
Skarmory is pretty obvious. Maybe alolan dugtrio? since she's in the desert... Excavalier or Scizor are also likely to be in her team. I'm not pretty sure about Magnezone or Bronzong. Lucario is also veeery likely. Empoleon maybe? Since "Rust thicker than water" and Empoleon is water/steel type, and is great controlling fire and ground-types. KlingKlang? nah, maybe no...
So, this is how i think Tania's Team will be:
Mawile
Skarmoy
Metagross
Steelix (Mega)
Empoleon
Aegislash (Ace)
What do you think?