spiritbomb. Lz does not focus on taking prizes, so you can slow them down a little while evolving your pokemon. Lots of collector to get eevee out, then evolve it. Maybe technical machine ts-1 once you evolve your bench till spiritbomb dies. Technically since the contents of your deck isn't public knowledge, you can choose to pull out less than 3 pokemon if your bench is getting full. Then throw in a ditto to lz whatever pokemon they have in their hands, make sure you get rid of whatever bts they have in play and use omastar to de-evolve that gengar for easier KO's. Throw in seekers to make them bring up poke's for your dittogar. Then palkia g x. Leave lz out for the counter so they'll think you can't play lz right and get surprised when you kill 'em
that might be one of the best ways to directly counter lostgar. But it won't really beat anything else, so top cutting will be hards if you don't face a single lostgar user.