Fusion currently can be upgraded but it doesn’t change anything to it, if memory’s not that bad.
So i thought about something that could add some use for that, instead of locking to LV1 :
Fusion could, at LV1, be usable between players if one of them have 1% of BP more or less but with each level it gains 1% more so 2% at LV2, 3% at LV3, etc… until 10% at LV10 (could be modified in the config files and these would be the default values, and can be deactivated making Fusion locked to LV1 and it’s old method idk)
I also thought about Potara fusion??
You could get a unique pair of potara earings from a Supreme Kai like Shin (U7’s Supreme Kai) and give one of them to a friend, you’ll also need to be good sided to get the potaras or even talk to Shin of course.
The potara fusion, unlike his Metamoran counterpart, isn’t a skill and thus can’t be upgraded because it would be useless as it discards the BP difference between both players (but it’s mainly because it’s an item ofc). To fuse with the potara earings, both players would equip a potara from the same pair in the scouter slot, giving more use to it too, and this will begin the fusion, merging both players in one.
Potara fusion will last (almost) twice as long but can be configurable like the Metamoran Fusion Dance and have a bit more power boost than the metamoran fusion dance since it is said to be stronger(I do prefer Gogeta to Vegito tho, don’t get me wrong), it’ll ofc have a longer cooldown like 10mins more?(also configurable)
As for the Supreme Kai, he could have his own world maybe, and the Elder Kai could be there too so you can get Mystic from him instead of North Kai. I don’t know how we could go there tho, saiyan pod ig