I... Honestly think the Geno and BK comparaison isn't necessary.
Their only common points are :
-Popular within the Smash fandom
-Created by another company but Nintendo should have their rights , since their companies don't use them much and are more fitting as Nintendo characters. (Microsoft at least did try a game and ported Kazooie/Tooie + some merchandise. Square didn't do **** with Geno , beside the remixes of Forest Maze and Goodbye Geno in the "Mémoria !" album.)
People love Geno because he represent the potential the Mario RPGs had , character and story wise. (same for Mallow , and the other original characters) There's also the fact that he was present within a lot of people's childhood and that his "possessed star warrior puppet" is just cool as heck for youngers players.
But as we all know , SE kept their rights and didn't used them because they didn't had any opportunities to do so. They need Nintendo and the Mario franchise to do something big with them. (I could argue that they can be used as summons in Final Fantasy , but SE never took the opportunity)
Also , I think that it's harsh to call him a secondary character.
He's a main character , otherwise other party members such as Peach and Bowser would be considered secondary characters and... The main characters would be Mario and Exor/Smithy ?
Geno is a main character , but he's not the protagonist , that title go to Mario.
A side character would be someone like Gaz , Frogfucius , Booster , Valentina , ect...
And yeah... Banjo and Kazooie have a legacy that
still live on today. If people are still talking about the duo , their games , and creating fan content for them , that's when a character have a real legacy for me.
That's a very important point for me : They're not at their best right now , but still have a ton of spotlight.
People still do let's plays of their games !
The point is , there is a ton of fan-content made for the duo and their franchise , so this show that a return and a new game would be GREATLY APPRECIATED.
And before people say "but average joe/jane won't know them !"... Who ****ing care ? Yes , familiarty is good for selling DLCs , but Banjo and Kazooie character's design alongside their moveset is far more than enough to sell them in my opinion.
Make them look cool and people will buy them ! THAT'S WHAT MATTER MOST TO MOST PEOPLE , THE CHARACTER NEED TO BE FUN TO PLAY AS !
I know they were veterans back in Sm4sh... But let's be serious for one second :
How many people unlocked
back in Melee ?
Heck , how many people unlocked someone past
and
?
Yeah , not a lot of people compared to how many copies of Melee were sold.
Despise that , the reception to Roy beeing Sm4sh DLC was
positive , and he sold pretty well because... He looked cool to play as ! And Roy's game wasn't even officialy released outside of Japan , FE6 has not been localized to this day !
But still , I could understand why Microsoft would feel skeptical about them to some extent. They have other big/or popular names that could completely work for Smash. (Steve , Master Chief , Cuphead/Mugman , ect...)
There is a risk by putting them in Smash , instead of another character that would push sales of actual games available of a franchise , and future games of thus said franchise.
However , remakes of Kazooie/Tooie would sell immensely well with BK in Smash. As long as they don't overprice these remakes , they have the perfect target audience (Nintendo's playerbase) and the perfect system for collect-a-thon (Switch , allow for short and long sessions.) , and a big nostalgia factor.
And these kind of games (especially with BK's designs) have an easier time finding an audience on Nintendo's consoles , than on their consoles. (There's bound to be more kids owning a Switch over a XBOX ONE because of the price and the Nintendo exclusives)
Also talking about Microsoft collect-a-thon on XBOX ONE... Lucky Tale on Switch when ?
The thing is , Banjo and Kazooie are the perfect candidate if they want a bridge to completely join Nintendo.
I'm no sales expert , but from what Iv'e seen the XBOX ONE isn't... Doing very well. Especially compared to the success of the XBOX 360.
Heck , besides Cuphead last year , I can't name a single XBOX ONE exclusive.
Of course , going from making consoles to only making video games is a big changment... But their situation remind me of the one SEGA had with the Dreamcast honestly. Not one to one , but there is definitely some big similarities.
So , to be simple ;
Banjo and Kazooie are the perfect character for a new start with Nintendo. They are loved , their games completely fit in with Nintendo's library and playerbase , they have potential for more games. (compared to Steve , once you buy Minecraft... That's it. Yeah they are others games , but they are spin-off. Steve will only sell Minecraft copies , where BK could sell Kazooie/Tooie/Nuts and Bolt/Threeie/Grunty's revenge copies , and more !)
Of course you could make an argument for Minecraft merchandise... But BK can easily have a ton more of merchandise with a potential return.
So this is my opinion on the matter , any criticism to make ?