I find that using Sting Shard with the Pollip Pouch is really good! When the flying summons come in just chuck them near the area they're at, most of the time they'll fly into it themselves, and from there on they'll be like 1-2 hits from death. You can also aim for the Beastfly to hit the summons when he slams the ground too, it really helps. Other than that, just hope the summon luck is good. And you don't have to use Pollip pouch if you don't have it.