What If Nightwing lead the Arrowverse?

I've previously made a structuring of the way Arrow would've worked if the CW made a Batman TV show instead of a Green Arrow show due to the influence of Batman that was spread into the roots of the show. However, that doesn't extend to how the rest of the Arrowverse would work, so today I'm replacing Arrow with a Nightwing series that would create a television universe in the same way Arrow did (though at a smaller scale)

Nightwing
Airing: 2012-20

Seasons: 8

Plot:

Protagonists:


 * Grant Gustin as Nick Grayson/Nightwing
 * Candice Patton as Barbara Gordon/Oracle
 * Willa Holland as Rose Wilson (S1)
 * David Ramsey as John Diggle/Spartan
 * Jesse L. Martin as Jim Gordon (S1-S7)
 * Katie Cassidy as Helena Bertinelli/Huntress (S1-S5)
 * Jordan Calloway as Michael Holt/Mr. Terrific (S1-S3)
 * Stephen Amell as Hank Hall/Hawk (S3-S6)
 * Minka Kelly as Dawn Granger/Dove (S3-S6)
 * Charles Melton as Garth/Aqualad (S6-)
 * Juliana Harkavy as Donna Troy (S6-)
 * Colton Haynes as Joe Wilson/Jericho (S7-)

Antagonists:


 * John Barrowman as Mark Desmond/Blockbuster (S1)
 * Manu Bennett as Slade Wilson/Deathstroke (S2)
 * The Court of Owls (S3)
 * Neal McDonogh as Damien Darhk (S4)
 * Josh Segarra as Heartless (S5)
 * Kirk Acevedo as Ricardo Diaz/The Dragon (S6)
 * Alexander Siddig as Ra's al Ghul & The League of Assassins (S7)
 * Willa Holland as Rose Wilson/Ravager (S8)

The Flash
Airing: 2014-23

Seasons: 9

Plot:

Protagonists:


 * Jordan Fisher as Wally West/The Flash
 * Malese Jow as Linda Park (S1-S4)
 * Danielle Panabaker as Tina McGee
 * Carlos Valdes as Cisco Ramon
 * Danielle Nicolet as Iris West
 * Tom Cavanagh as Harrison Wells
 * Brandon McKnight as Ronnie Raymond/Firestorm (S6-)
 * Kayla Compton as Caitlin Snow/Killer Frost (S6-)

Antagonists:


 * Tom Cavanagh as Hunter Zolomon/Zoom (S1 & S8)
 * Teddy Sears as August Heart/Godspeed (S2-S3)
 * Grant Gustin as Wally West/Savitar (S4)
 * Chris Klein as David Hersch/Cicada (S5)
 * Neil Sandlands as Clifford DeVoe/The Thinker (S5)
 * Sendhil Ramamurthy as Ramsey Rosso/Bloodwork (S6)
 * Efrat Dor as Eva McCulloch/Mirror Monarch (S6)
 * Rick Cosnett as Eddie Thawne/Cobalt Blue (S7)
 * Tony Curran as Despero (S8)

Supergirl
Airing: 2015-21

Seasons: 6

Plot:

Protagonists:


 * Melissa Benoist as Kara Zor-El/Supergirl
 * Chyler Leigh as Alex Danvers
 * Mehcad Brooks as Val-Zod
 * David Harewood as J'onn J'onzz/Martian Manhunter
 * Jeremy Jordan as Jimmy Olsen
 * Joshua Orpin as Conner Kent/Superboy
 * Brandon Routh as Clark Kent/Superman

Antagonists:


 * Peter Fascinelli as Maxwell Lord (S1)
 * David Harewood as Hank Henshaw/Cyborg Superman (S2)
 * Odette Annable as Sam Arias/Reign (S3)
 * Melissa Benoist as Linda Lee/Red Daughter (S4)
 * Jon Cryer as Lex Luthor (S5)
 * Peta Sergeant as Nyxlygsptlnz (S6)