Since you're gonna be childish (More than a zoomer apparently), I'll not reply as well.
Gives Sonic, a rebellious cool character, someone to rebel against
Knuckles already does that and better. We're off to a good start, lmao.
A mentor to Tails
Sonic already does that. Like wow. Even if you argue that he's not really a mentor because Tails just follows him, that still doesn't justify the existence of a mentor. Literally no character in this franchise has a mentor, but Tails needs one apparently? And Tails being a mechanic doesn't stop him from doing cool shit. See Tails adventure.
nearly as powerful as Sonic, and therefore able to demonstrate how powerful enemies are
If she's not as powerful as Sonic, why wouldn't Sonic himself be able to demonstrate that by struggling with a fight? Why do you want Yamcha? Also, it shows the OPPOSITE of stakes to roboticization since she actually benefitted from being a cyborg and even turned into a little baby bitch when she was healed.
A low-tier rival character, and effective foil to make Sonic look cool as he defies his expectations
Ah, "character made to make Sonic look cool". Another Yamcha. Incredible. You don't need comedic relief characters if the main characters are funny already.
Sage but good and not pedobait.
Nicole has absolutely nothing to do with Sage so idk what you're talking about. Do you really think both Sage and Nicole boil down to "AI girl"? That's a pretty shallow view, even for a diaperfag.
Imagine if I went to ATLA and took their freedom fighters there (The ones with Jet, the duke, etc...), and said "Hey, these guys should join the Gaang and be a team of like, 10 people" and then made up a bunch of retarded reasons as to why it's actually to have these useless jobber faggots there at the final battle with Ozai. That's what you're doing, and it's hilarious.