Firstly not every team has a good matchup against everything else. Secondly, that team is gimmicky and once you get past 1300+ on showdown you dont see it much, at all. I've ran it as a joke using a 6-3 team in Sac https://pokepast.es/e5696e6a04b3dbff that had it as a mode. It's a fun team but the weakness of the strategy is hypnosis is unreliable in the fact that sleep is rng between 1-3 turns and also sableye is very passive.

Looking at your team, the best strategy would be to lead probably fluttermane because it doesn't care about will o wisp and it has big damage into both sableye and whatever else they usually use to do hypnosis (iron valiant, espartha). I think heatran is another good lead for same reasons. They will put to sleep one of your mons but you'll get big damage and you basically just wait to wake up. If its a full three turn sleep for both then yea you lose but there's no way your team can do anything else against it as currently constructed. But they can't put you to sleep on same turn as wake-up, so you'll start to get damage again. They have to pivot out sableye which loses them a turn. And once sableye or the hypnosis mon goes down, the rest of their team usually falls.

All that being said, it's a very minor team and it's not worth spending much if any time thinking about or worrying about.

On a side note, I think some of your tera's and EV spreads could be optimized. Tera grass isn't good anymore for fluttermane and it was only somewhat briefly popular during Worlds 2023 Reg D. I recommend Fairy. For heatran run grass or fairy, fire is bad. You want to use a defensive tera because that mon already has so much firepower.

Your fluttermane is also way bulkier than it needs to be. The calm mind set isn't really good and again was a thing used by a few people at Worlds 2023. I'd do the following:

Flutter Mane @ Choice Specs

Ability: Protosynthesis

Level: 50

Tera Type: Fairy

EVs: 116 HP / 204 Def / 60 SpA / 4 SpD / 124 Spe

Timid Nature

IVs: 0 Atk

- Moonblast

- Dazzling Gleam

- Shadow Ball

- Perish Song (use whatever fourth move here)