So just going off of this list this is mostly a combination of gunplay and counter-focused characters, so I'll take a stab at some central ideas from each character that could be applied.
Cable: Grenades, Scimitar (please god no)
Hol Horse: Glass shatter, air bullets, maybe something crazy like the pipe bank shot super
Chris: Grenades (special), prone stance, grenade launcher super
BB Hood: Mines (HK buttons), Missiles, guard cancel teleport, Huntsman super (maybe sub in Medici goons)
Justice: Tail counter, nukes (maybe with those perfume grenades?), mayybee Strike Back Tail, mayybee Gamma Ray as a really out there level 3 or level 5 to go with the hidden mechanical body theme.
Genjuro: Card slash rekka and projectiles subbed with the doilies
Darkwing Duck: uhhhh
Cammy: Hooligan Combo, Cannon Revenge, Killer Bee Assault (guessing this specifically is why mvc2 cammy was cited instead of SF versions)
Meta Knight: Dimensional Cape (Down B), Darkness Illusion (Brawl Final Smash)
That's what I got. Keep in mind how Umbrella turned out was pretty different from the initial speculation so I'm not getting too carried away this time. It also helps that I don't really play any of her inspirations this time around.