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I want you to know that I strongly oppose to you using this team to get on the leaderboard. If you were trying to get the Starf Berry or whatever, that's totally fine. But I gave everyone all the info you need to get to 1000+ with this team. You can spend 100 hours getting there, but it isn't an accomplishment. We have the leaderboards to demonstrate and reward great teambuilding and strategy in play. With all of the info I've provided, you can't demonstrate either of those things. A computer with a pretty simple algorithm could play with this team and get a huge streak. The time you spent breeding Whimsicott is nothing compared to the time Turskain spent getting good at the Maison, and I'll be kind of insulted if you wind up getting a better Singles streak than him with this team. That said, if you want to try it out for your own amusement and don't intend to aim for the leaderboard, that's fine with me.
228 Speed EVs on Durant lets it outspeed everything in the Maison that you encounter after battle #40. The fastest Pokemon in there is Scarf Manectric (Manectric 4); 228 Speed EVs lets Durant outspeed it by one point. Of course, you'll be taking its Scarf with Switcheroo anyway, so outspeeding Scarf Manectric probably doesn't matter, but Durant generally isn't using those extra EVs anyway.
228 Speed EVs on Durant lets it outspeed everything in the Maison that you encounter after battle #40. The fastest Pokemon in there is Scarf Manectric (Manectric 4); 228 Speed EVs lets Durant outspeed it by one point. Of course, you'll be taking its Scarf with Switcheroo anyway, so outspeeding Scarf Manectric probably doesn't matter, but Durant generally isn't using those extra EVs anyway.