...So, if I may, I would like to offer a counter to the perception that Nintendo picks DLC characters/costumes based entirely on marketability. I find this notion silly, as evidence to the contrary can be found through the simple act of looking at the roster.
We have Joker, Hero, Banjo&Kazooie, and Terry Bogard so far. Of those, the only character who falls into the mold of a highly marketable, breakout hit character in the height of their popularity is... Joker.
-Hero and Dragon Quest are popular in a way that cannot be overstated... in Japan. But Smash is an international game, and all of us will remember quite clearly the complete and utter lack of enthusiasm the Western Smash Community had in regards to Hero's inclusion. One might argue that Smash is bias to Japan, but if we're talking corporate greed and big money decisions, Japan only makes up ~20% of the Smash Ultimate install base. Surely they could have pushed something with wider appeal.
-Banjo&Kazooie were once a big part of the Nintendo brand, and was a beloved series with a fervently loyal fanbase, for good reason. That said, regardless of one's personal feelings toward B&K, they have not truly been relevant since the early 2000s. They were and are a footnote in the story of gaming history. A prominent footnote, but a footnote nonetheless.
-Terry Bogard... I could talk about Terry's -and by extension, SNK's- history and relevance to gaming... but all I'd be doing is re-skinning what I just said about B&K, except even less marketable due to lack of vocal support. Terry is near the polar opposite of a shill pick.
If Nintendo's goal was to make all the money by grabbing eyes and exploiting recent trends, 3 of the 4 characters in the Fighter Pass would not be there. We'd instead have Joker, 2B, Minecraft Steve, Fortnite guy, etc. And sure... many, many people in the greater user-base would likely prefer such a line-up, but it is demonstrably not the brand of content we've been getting. Nintendo clearly feels they have very little reason to exploit existing marketability.
Unpopular, Unknown, and Irrelevant characters become Popular, Known, and Relevant through Smash. It has been happening since Melee. It will continue to happen. It is perhaps the greatest power Smash wields, and one Sakurai [and now Nintendo] are evidently wont to use.
Do they want to make money? Obviously.
Do they sell things strategically, using methods that incentivize larger purchases? Yes.
Do they choose characters and costumes to cash in on current market trends? Signs point to no.
