@kevinds:
The supernova seem to exist as a foil to Luffy’s growth, and outside of Kid and Law, none have really been “rivals” to Luffy. Zoro is a special case since he is the first strawhat and follows Luffy for a bigger reason than blackmail. Like Mihawk said to Luffy, Luffy’s dream is far more ambitious than Zoro’s. Zoro knows that if he follows Luffy and if Luffy doesn’t stray, Zoro will achieve his dream, so it makes sense to follow Luffy specifically. Blackbeard is Luffy’s only real rival now, but he’s worst gen, not supernova.
The supernova showed what could have happened to Luffy in the New World. Hawkins, Apoo, Killer, and Kid made it clear that even an alliance of supernova were no match for one Yonko. So that was working in the background while Luffy and Law built their alliance to add tension. Similarly to when Luffy worked with Capone. Bonny is going to be a tie to the revolutionaries and Kuma (who all the SHs need a resolution with), and Drake should function the same for the Marines. If he stays on Luffy’s side after Wano and speaks to Coby some more, he may be the highest level ally in the Marines, unless Garp is the head of Sword.
Drake does have some interesting similarities to the Botanist crewmate in Oda’s drafts (mostly the headpiece), but he was scrapped for Robin, so I don’t think he was “reused” for Drake and it’s just a coincidence. I see Drake-for-nakama like I see Smoker. It’s contrary to his character who is focused on duty, and Drake wouldn’t abandon Sword just like Smoker would never abandon Tashigi and G-5. I also don’t think it’s in Oda’s interest to have a character with ulterior motives join the crew. They need to be behind Luffy 100%, and I don’t see Drake or Smoker giving up their ties to the marines.
I feel like the point of supernovas is to show all the possible ways someone could succeed (or fail) in the NW.
Kid took the "Luffy but without training" route and lost an arm for the trouble, plus got his own first mate crippled.
Law took an equally ambitious approach but with a long term preparation and a plan similar to Blackbeard's, so far with positive results (but not exactly how he intended due to his own personal vendetta against Dofla and Luffy's unpredictability).
Bege had a whole different goal to begin with, join a big organization and assassinate their leader for the lulz. He failed at that, but ended up gaining a family and leaving the NW happy.
Drake was not even a pirate, he joined the race as a disguise for his mission as a marine.
Hawkins went in with ambition but gave up when his cards showed he would die if he didn't join a yonko.
Apoo didn't even need cards, he joined Kaido very early and then used his status as a supernova to join other ambitious supernovas in a yonko-killing plan and sabotage it.
Bonney also seems to have a whole different goal too.
Not sure about Urouge's goal, but he also went against Big Mom and got the only major victory of anyone besides Luffy, though he still lost afterwards.
It's interesting how, aside from Apoo, none of them went in just to join the Yonko (and maybe Apoo actually had ambitions for a while, until he didn't). They all came intending to rock the NW's boat, each one in a different way, and have mostly succeeded pretty well.