Predictions on November's community day?
Bagon or Slakoth would be very nice :D
Answers
If ralts eventually gets one, as November's liektoy to be cyndaquil, gardevoir wont get anything to make it relevant unless they make a fairy charge move a fast moves, of which theres no precedent, so if it got one, it wouldn't be useful beyond what it already has.
I'd say its Cyndaquil for fitting the pattern, and maybe bagon or trapinch after wards in December. I dont think slakoth would get one as it directly would contradict why niantic gave It yawn, and if they did keep the spirit of the ability truant in a new fast move, it still wouldn't be good
The only unreleased Fairy move that would become a fast move is Fairy Wind, which Togekiss is likely to learn. Gardevoir, however, can’t learn Fairy Wind in the main games so it won’t learn it in GO. They’d have to change a current fairy charge move to a fast move, like Dazzling Gleam or Draining Kiss. If they changed Dazzling Gleam to a fast move that would probably upset many people who use Blissey.
Gardevoir has one last hope in Misty Terrain, akin to what they did with yawn buy turning a non-attacking move into an attacking one (yawn still does damage despite having 0 attack). But I think that's very unlikely.
The slakoth family might still get a CD CHARGE move, so it's not completely impossible.
I still bet on Bagon being the next one after Cynda.
Depending on if Ralts got a CD before or after Gen 4 they'd need to do something for Gallade as well. A fairy move won't help it being Psychic/Fighting. It would be interesting to see if they made two distinct exclusive moves that were evolution dependent or if they just picked a singular one both could learn.
They could do fun things with research too, like have some tasks reward the Dawn Stones needed or have research encounters be exclusively male.
It's going to be either Cyndaquil or Totodile.
I don't know if there will be a typical Community Day in December as the typical days for CD are really, REALLY bad in December (either the weekend right before X-Mas, when people are doing last minute shopping OR travelling after school gets out, or the weekend before New Years, where people are travelling home OR are far from home and not in places great for CD).
What I think would be really, REALLY cool is something like a "12 Days of Christmas" style where each Weekend day from the 15th to 30th will have the previous Community Day Pokémon spawning in huge numbers, with the moves they had during their Community Days. And each of the 6 days would have a different bonus associated with it., with Triple Stardust and Triple XP being used twice. (so 3x Stardust/3x XP/2x Candy/4x Hatch Distance/3x Stardust/3x XP) That would give everyone 6 chances to get the Pokémon they missed during the last CD's and 6 chances to evolve to get those moves.
That's what I'd do if I was Niantic.
Cyndaquil if they keep pokedex order. Hard to see why they wouldn't.
Some CDs have been earlier than around the 20th day, they could easily just put November a week earlier and December halfway through the month. Long wait until January CD doesn't matter because most people have holidays in between and there's going to be a Christmas event.