what I can recap the story for the Shantae Series
GBC: Shantae and Risky had their first encounter with each other. Also, Risky's plan of using the 4 elemental stones to power a steam engine to rule Sequin Land. Shantae taps into her Genie Magic and had a chance to become a full fledged Genie after destorying the Giant Mecha Tinkerbat and the Final Fight with Risky, but turned them down to stay with her friends.
DSI Risky's Revenge: Risky steals the Magic Lamp Artifact that Mimic uncovers to use it for her own use. Shantae gathers the 3 magical seals to prevent Risky from using the Lamp's power. Upon fighting Risky, she uses the lamp to steal all of Shantae's genie magic (and not imprisonment since she is a Half Genie). The Lamp used the stolen magic to make Nega Shantae in the final fight and Shantae was forced to kill her magic counterpart. Upon the dark version's defeat, Shantae is now fully human and Risky retreated back to the seven seas to plan a new scheme.
3DS Pirate's Curse: With Shantae now being fully human, she still has her duties as Scuttle Town's Guardian. However, the Genie's long enemy, The Pirate Master, is start to call his original crew to come back as his magic strength is returning. Upon Shantae being fired from being a guardian again (how many times can the mayor screw up for his town?!), she was greeted by Risky again with her questions the whereabout of her weapons. Not long she finds out her old master is returning with the tinkerbats turning into Cacklebats thanks to the dark magic. With that, Shantae and Risky team up to stop the Pirate Master from returning. Eventually, the Pirate Master returned to spread darkness to sequin land with Risky captured and waiting at Scuttle town's Castle for Shantae (the ending depends if you collected all of the dark magic or not.) In the final confrontation against the Pirate Master, he requests a trade: the dark magic for Risky's life. Upon the trade, Shantae finds out that her magic was not destroyed after the last battle and used to finish the Pirate Master one and for all.
Wii U & Switch Half Genie Hero: Shantae had a Dream of the Genies contacting her about a disaster coming for the Genie Realm and she wanted to know about her mother's whereabouts. Waking up, Mimic was designing a weapon to let shantae have a break from her guardian duties. It didn't take long before Risky made her next attack towards the town and a Tinkerbat stole the plans. Shantae performing her duties, she defeat risky and retrieved the plans back. There, she was tasked to get the parts for Mimic's invention and was fired as a Guardian Again (Again with this Mayor Scuttlebutt?!). With having to save a village and the Mermaids, retrieving all of Scuttle Town's Memories, Stopping a Magic Carpet theft, and defeating the enemy of unspeakable horror (no.....its just Squid Barron), she retrieve the parts for the invention. Though the invention was actually meant for risky to use by inverting Light Magic to Dark. (With DLC, there is an alternative story with Risky and her friends reaching out to Shantae during her Dark Magic corruption. Also different endings if you did all the Barron's side quest to get a Magic Converter made by Mimic or not). Reaching Risky's Hideout, she tried to stop the Dynamo to enter the Genie Realm and corrupt the Genies. With the Dynamo having control over the Genie realm, she had no choice but to destroy the Dynamo and the Genie realm. Upon the Dynamo's destruction, Shantae and Risky fled from the Volcano Hideout. (Again, the ending is different if you did the Barron's errands or not. Its if Shantae does or doesn't know about the fate of the Genie Realm after the Dynamo being destroyed.)
???: That is up to Wayforward on the next entry in the series.