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I don't think you should worry about that. It's still going to be a gimmick move used in very rare occasions. Plus Whirlwind/Roar would be better counters to it than crappy moves like Magical Leaf
Gyro Ball would be a good option on the curse set. The Swords Dance set, I don't think it will work. Nattorei's low speed and that crippling fire weakness pretty much ensures you'll get killed by any fire type that switches in.
One problem with that: attacking your own pokemon in doubles isn't a very good strategy. And since this strategy will be pretty obvious, Primeape/Tauros will get obliterated by the opponent before it can do anything.
I think a SubCM set could be really effective on this guy:
Oobemu @ Leftovers
Nature: Bold(+Def, -Atk)
252 HP / 4 Def / 252 SpA or 4 HP / 252 Def / 252 SpA
Ability: Analyze
Psychic/Psycho Shock
Hidden Power Fight/Ground
Substitute
Calm Mind
This set takes advantage of Oobemu's high Special...
Actually Salamence and Garchomp(maybe Latias too) will probably be OU in the beginning of the new metagame so unless they are banned again Ono won't be as overpowered as you seem to think.
I've listened to it and it's mediocre at best. The only songs that stood out for me were The Talisman and Starblind and even then, they weren't that good. The many long/boring songs ruin the album imo