For me - Zelda series.
In the last 18 years, it's impossible to anticipate anything without at least one person making a "Dawn of the Final Day" joke. The mask itself is incredibly recognizable. People rioted when he wasn't included in Hyrule Warriors. Meanwhile, Midna from TP got the most characterization by far for any of Link's companions, was actually the title character and more important to the story than Zelda herself, and got two separate movesets in Hyrule Warriors.
On the other hand, there are two Smash characters who still never made it out of Japan outside of Smash
, and several characters who have exist in one game only outside of Smash
.
People like to point out that "Fire Emblem has an entirely rotating cast, so they should have one (or three) characters from each game, but Zelda has the triforce trio and unimportant one-offs" as an explanation. It really seems like some series are allowed to get one-off characters, but no matter how good or iconic a Zelda characters is, the best they can hope for is an assist because they're not in every other game.