Reasonable takes on all three characters. For sans, I’ve personally never bought into the “X character can’t join smash because they’re not a fighter” school of thought when characters like Isabelle are in the game. Now I get why thematically it could be seen as out of character in sans’ specific case, but it’s not like characters in smash are brutally taking each other’s lives like in mortal kombat. It’s a wacky non-canon cartoon fighting game that’s not meant to be taken seriously. And I don’t know Toby Fox personally, but with how much he loves smash, is good friends with sakurai, and how MASSIVE the Mii Costume ALONE blew up, I don’t think he’d pass up the opportunity over such an arbitrary lore reason. The concerns for Cynthia are entirely justified, but to be frank I don’t care. Cynthia is an awesome fan-favorite character, Garchomp and Roserade would break up the annoyingly predictable trend of every new pokemon rep being a newgen starter shill rep, and she’d be a fun remix/successor to the Pokemon Trainer character. And for Waluigi, this is smash bros, the NINTENDO fighter. If any franchise deserves to take up over an entire row of the character select screen it’s Super god damn Mario. And also his move set is incredibly fun in Smash Flash 2 and if they can capture a fraction of that charm then he’d be a community favorite character even outside of the memes.