- Puyo's cross-generational brand recognition in Japan
surpasses Sonic the Hedgehog and competes with the likes of Sanrio. It was so popular in the 90s that it
almost had a theme park. It stands as Sega's second largest franchise behind Sonic himself.
- Puyo Puyo has been on EVERY Nintendo console other than the Virtual Boy, and it was supposed to be on that one too before it flopped. It continues to have a significant presence on Switch with Puyo Tetris 1 and 2, Puyo 1 and 2 through Sega AGES and Puyo 2 on NSO as well (notably added over the readily accessible Kirby's Avalanche, Nintendo's own Puyo reskin).
- Much like Terry, Arle is a foundational icon of her respective genre and incredibly popular on another side of the world. Puyo 2 in particular was the biggest arcade game since Street Fighter 2 in Japan during the 90s.
I think these points make a pretty strong case for Arle - I'm not "expecting" her perse but there are a lot of great reasons to bring Puyo into Smash.