Hm, all right I'll explain the best I can and my thought process behind it. As for Meowstic, I'm actually liking it more due to the lack of fire/ground weakness so I'm going to be training one up.
The initial idea for the team was "can I take a few Pokemon I like and work something around it?" That's the first part, much harder part then after is team synergy which I'm still stumbling along as I go to see what works. While my personal philosophy is to have fun with it, I think there should still be some thought behind the team and not just slapping favorites on and calling it a day. Rapidash and Seaking are some of those, but I realized they simply just don't hit hard enough on their own which is how the Safeswag idea came into the works. Most of my team is rather frail as well, so I opted to find something else I like that has Tailwind and hits hard when that job is done. That's how Braviary came in. So a brief excerpt on each.
Rapidash (Likely to be replaced with Arcanine)
There's not much to say about him; he's very straight forward. After Swagger takes effect, he can hit things reasonably hard. Since people loved to hit Klefki with fire moves, I can usually get a safe switch after wards. Without Swagger, he doesn't hit nearly hard enough unless whatever he's against is already weak to fire. On that note, Mega Aggron I had no idea was so buff; they took a plus two Fire Blitz and it did at most a bit more then half or so.
Like plenty much all the team mates, he's frail so its kill or be killed. I was thinking of replacing them with a Arcanine, not only do they hit a lot harder off the bat but they have a lot more bulk. That, and they get priority. In triples most Pokemon get their lives destroyed in one or two hits anyway unless your name is Cresslia. Morning Sun was suppose to be for healing, but considering frailness may be better to replace with something else like Wild Charge.
Braviary
My primary tailwind setter. And Defiant I've found is incredibly useful since a lot of people like to run intimidate. They don't even need swagger most of the time to kill things unless something is really bulky. Brave Bird cuts its life really short though. That was the main reason for Roost, just to keep it a live a bit longer. However, that doesn't work out like it should most of the time so Rock Slide over Roost sounds better. As I'm learning as I go, he simply doesn't have the bulk and people gang up on him to kill them quickly.
Focus Sash was to ensure Tailwind, but I honestly think I need a different Tailwind user since a lot of times he uses it, then dies as people have a habit of ganging up on it. Aerodocatyl might be better at that job, its a lot faster even if it doesn't hit as hard and its best flying move is Fly which is a two turn move. It also has things like the Elemental Fangs and Earhquake so that's something to consider on my part.
Talonflame apparently hates the poor guys guts because they always go after them.
Klefki N/A will replace with a Meowstic soon. The idea is obvious to boost the physical attackers that need it the most. The screens also boost their overall bulk a bit. In Doubles/Triples I know its nerfed but not sure how much. Also, Safeguard is good for things like Dark Void spam and other statuses. Getting paralyzed or burned would be the kiss of death for many of the team members. There's also the fact Meowstic also learns Trick Room if I want a way to reset it when encountering those teams.
I lost a match with a scarfed Dark Void Smeargle not too long ago, but I'm not even salty about it. The lead made it obvious that the Fake Out was coming on my Klefki so I could have trusted my gut, double protected and withdrew them so I could safely put Safeguard. Ever since that and others I've gained more bias towards Safeguard.
Seaking
I wanted a water type, and going by the original idea I began scanning around Serbii for stats, move pool and abilities. Originally, I thought I was being clever and put a Weakness Policy on it, bait the lighting attack..only for nothing to happen. Doesn't work with Lighting Rod apparently as I found out the hard way, which sucks.
Aqua Tail with STAB hits decently harder after a boost, Mega Horn is for things that resist water and since its super effective against something's and has more base power then Return I figured why not? Plus it hurts Cresslia. Protect is on there for obvious reasons. Agility..I'm unsure about. On one hand it has helped when I gotten the chance to set up(doesn't happen often Triples since its so fast paced) but on the other, I kinda feel a Ice Beam would be better for things like Garchomp and Landorus after the special attack boost. A lot of times it saved my Braviary from certain doom from a Rotom-W on the incoming T-bolt.
I've considered Swampert as a replacement or Kingler both are water types and they both get Wide Guard. I think it blocks stuff like Dark Void, at the least Heat Wave/Rock/EarthQuake Spam so that's a thing. Kingler has good physical defense but doesn't have special to save its life so likely the former. That and the necessity to run Protect on everything in this meta kinda makes it suffer more from Four Move Slot Syndrome.
Medichan
I love this dude. He's not the fastest but man does he hit hard. They are probably the MVP of my team as they don't ever need the boost most times unless I really want to one-shot something but not sure if it will or not. Ice Punch is for dragons like Garchomp or Dragonite(I haven't really seen much of the later honestly) High Jump Kick and Zenheabutt are just STAB moves. The later is really only useful for killing fighting types, the first does a good job of murdering things like Heatran..when it doesn't miss.
I think he's more or less fine on this one.
Whimiscot N/A
After thinking of what Kashinn said, having two Tailwind users along with Prankster may not be the best idea considering my team's make up. Though I'm kinda at a loss of what other Tailwind users I can use if I replace Tailwind on Braviary with Rock Slide or something. Since I like using more lesser used Pokemon on average I'll have to chew on it a bit longer. There's also the fact things that sound good on paper aren't so much in practice as I've learned.
If anyone has any suggestions for lesser-used Tailwind users I'm all ears.
On a side note team's main weaknesses I've noted:
-Frail, requires set up for some members before they get going
-They hate Talonflame who snipes at the weaker links when they're weakened.
-Moves that hit the entire party such as Earthquake
-Trick Room