It's an excellent team! I'll try it later for sure!a0161613 Rain is fun to play in Singles and still good! That said, you can't expect to bring a full rain team and hit the top of the ladder. When playing rain in BSpot, there are a lot of threats that can still overrun Mega Swampert.
My tip is to not think of Rain as your sole win condition. Rain should be treated as a little boost which might help Kingdra/MSwampert/Scizor etc. As for me, I found that adding a second Mega helps a lot so that I'm not overly reliant on Rain. Namely a mega that deals with things that Swampert can't. There may be other ways around this though, such as ensuring that you have answers to Swampert checks. Again, you'd build a team not to focus on rain entirely but one that can thrive without rain too.
At the start of my team building I had both Swampert and Kingdra and ran into the problem of over-commiting to rain sweepers. Weather teams like everything else needs to be flexible!
If you don't have a team feel free to steal mine and tweak it to your liking! To adapt to the meta I've swapped Salamence for Mega Manectric but there are a lot of ways that you could make it better!
I was thinking of a similar set up on doubles and triples, with the logic of Prankster rain dancers. First choice was Klefki or Sableye. I'd be reluctant to include Scizor or Ferrothorn but I recognize they would be excellent in this meta. Thundurus maybe?
It's a shame Dragonite didn't work out, it's perfect in theory but I wonder if Tornadus could replace it.