I, thank you kindly for your in-depth analysis.
For the slow mon team I have going on, This is where Peach (Pachirisu) comes into play. What usually happens is I send out this little wonderful creature and go straight for the nuzzle or Sweet Kiss. When (no ifs about it) she lands either moves and receives no damage in return I go for the parafusion hax then switch out to one of my sweepers and begin to set up from there to run away with the battle. And While this is exploitable, Since she's with an Air balloon, the AI in the game will consistently use ground type attacks in a futile attempt to hit her where she laughs with Super fang as the enemy slaps itself. Though I believe Porgon 2 can do her job better, His move pool would consist of Trick Room, T-wave, Tri-attack, and Either Swagger or Secret Power with an Eviolite.
Donphan is there as more as a Bulky sweeper, I have used Donphan in Smogon before and had Relative success. I have been looking for an Assault Vest to equip it on him so he can survive Special attacks without relying entirely on Sturdy to keep him alive. Though when this Manly creature hits, he hits extremely hard. It's a rare sight for Donphan not OHKO something when I used him, But even then He's a good counter part to Peach, especially in doubles. Though I will Take into consideration about Flygon/Mamoswine. Though for me personally, I always loved having a Weavile as a counter for Dragon spamming, though If I remember correctly. There's no sneasel obtainable.
Mawile, I love this mawile. I can see where your going with and I have first hand experience the soul-crushing experience of her getting demolished by those moves (namely fire punch; since the exploit above is still possible with Mawile and ground moves.) She came in later into my game to replace my Granbull who would do the same job but slower than she did. I conteplate making my Leafeon into a Slyveon instead to replace Mawile but I wanted to experiment a bit with this team. As for Gardevoir, I have no clue where to locate a Ralts, so I was maybe considering a Slurpuff instead with a belly drum set.
For Noivern, I agree. I think tailwind would be much more beneficial for this team as a more last stand support move. Especially if I do ever decide to make Trick room Porygon, where if he Falls, noivern can still allow the remaining sweepers to pull through.
Im not entirely sure about the Leavanny or Gogoat, for if anything they're a bit more boring. Though i never really given Gogoat a try, I'll most likely test him out. Haru here, was a replacement for my Venusaur to be a more sort of Glass cannon kill all things. He can take a hella of a beating with physicals but specials destroy him.
Ah Instead of energy ball I tend to lean more towards Solarbeam since She can fire it at will and yes, She had Will-o-wisp before, but I accidentally replaced it with safeguard (Woops) while I wasn't paying attention so I kinda just rolled with it.
