Gagaga.
And I don't mean support from other archetypes, I mean better support cards for Gagaga. Because, I mean...half of the released Gagaga cards are either almost good, bad, or incredibly situational. Especially the Spells/Traps.
Gagaga Wind, for example, special summons a Gagaga Monster to the field, which is great...except for the fact that it makes them level four. Making it useful for only one member and easily replaceable. Or how about Gagagadraw, which lets you banish 3 Gagaga cards and draw two, kind of going against the whole purpose of Gagaga Mancer and Gagaga Revenge, and stunting the usefulness of Gagaga Sister and Gagaga Clerk. And then there's the debatably debatable Gagaga Academy Emergency Network, which is good (especially thanks to Sister), but is really limiting with its dependence on having no monsters on the field and after the fact, not allowing the user to special summon.
But I know it won't get support because already has so many cards and the ones that are versatile meld well with other archetypes. There are just so many Gagaga cards that won't see any use in even decks made for fun. Heck, my non-Xyz Gagaga deck doesn't even use most of those, and theoretically it'd get the most out of them.