For this you have to understand some things about this alternate Steven Universe "Universe". First off, once Rose Quartz was recognized as a threat, the rest of the Rose Quartzes were used to in a desperate attempt to defeat Rose instead of them being bubbled. Also, Gems aren't assigned to a Diamond based on color, but instead based on what Kindergarten the Gem was made in. That means a Sapphire can belong to Yellow Diamond. And finally, instead of sending the Ruby squad to retrieve Jasper, this team of Gems was sent to get Jasper and arrest the Crystal Gems.
In an alternate ending to "Barn Mates" a drop ship appears trough the clouds chasing Peridot after she tries to leave. The ship had locked onto Peridot and followed her back to the barn. Lapis attempts to fight off the ship with the new pool Peridot installed but fails. The ship lands. Clouds of pressurized air stream out as the door opens. Out comes a Rose Quartz. Steven: MOM?! Following the Rose Quartz is a Peridot exclaiming log dated and recording the area. Proceeding them a Sapphire, Ruby, and a Bismuth. Lapis grabs Steven and Peridot and flies into the barn to hide. The warp pad activates. Garnet, Amethyst, and Pearl arrive and spot the Homeworld Gems. Pearl: Cease in the name of Rose Qu... Pearl spots the Rose Quartz among the group and is speechless. Garnet: Why are you here!!! The Rose Quartz looks over and replays in a deeper but still elegant voice, Rose 4XB: We are here for you. The Rose Quartz charges towards Garnet at full speed and pulls her weapon from her Gem on her forearm. A oval shield appears baring a large spike in the center. Garnet summons her gauntlets and commences to fight. Amethyst joins in. Amethyst: Nobody messes with the Crystal Gems! Garnet: PEARL! Pearl: Right Pearl, stares as the Rose Quartz as she pulls out her spear. The Bismuth runs over followed by the Ruby. Bismuth 2XD: AAAAAAAH! Ruby 7XE: We'll get you! The fight commences. As the Garnet, Amethyst, and Pearl are all fighting Peridot, Lapis, and Steven sneak out of the barn. Lapis uses the pool to make a large arm to attack the Peridot.