>>58181558Since you posted her form here's the quick spoiler version:
In SM you play 3/4ths of the game until a special location with a cutscene, and then press A at a portal to go the world with the jellyfish to see Lusamine go mad and fuse with a jellyfish. You then fight her 5 pokemon team that all have a Totem aura boost to a stat. She then goes on a boat with a dialog box saying she's off to see Bill and his pokemon separation device in KANTOOOOOOOO since there's still traces of jellyfish in her system, never to be seen again on your save file.
In USUM when you get to the end of the cutscene the portal poops out Lusamine and Guzma like a butthole before a fight that ends with Solgaleo/Lunala being non-consentually penetrated by Necrozma who absorbs them, forces a fight with cool music, and then another cutscene happens showing him fleeing away into the portal. You eventually go through the portal and end up in Ultra Megalopolis which has concept art showing it as a metropolis with skyscrapers, but the only ULTRA new location is a street that leads to a tower that takes you to the stairs on the roof that take you to the fight on a platform with Lv70 Ultra Necrozma. The fight is unbalanced so you have three types of players: Teams with type advantage saying it was fine, teams that did not have type advantage saying it is unbalanced, and people who backtracked to catch a Lv4 Zorua to use its ability to trick the AI into Psychic moves on a Dark type before using Foul Play. A pretty shit location and fight that was a huge disappointment for people expecting ULTRA CHANGES. Necrozma later appears in a crater Yamcha'd and you finally have the fight to catch him since you couldn't previously. Lusamine stays around at the end of the game this time since she doesn't fuse in USUM.
So to answer your question about the Lusamine she is a better character in SM, but USUM has better gameplay like Ultra Space locations for all legendaries of a version and Rainbow Rocket.
