I don't know if there are any active MKDD players in the area, but I know of this event:

https://www.facebook.com/events/476587482452419/?ref_dashboard_filter=upcoming

Date:February 22, 2014

Signups 6:30pm - 7:30pm, Brackets Start at 7:45pm

Location:
YESTERcades
80 Broad Street
Red Bank, NJ 07701

Parking is free on any street in Red Bank after 6:00pm (even if you see a parking meter).

Game(s):
Super Smash Bros. Melee (Gamecube)
Mario Party 4 (Gamecube)
Mario Kart Double Dash (Gamecube)
Sonic Adventure 2: Battle (Gamecube)

Pricing:
Venue Fee: $15.00 (Gives in/out access to all arcade games and facilities until closing)
Melee 1v1 Tournament Entry: $5.00
All other games/events are free to enter/participate with cash prizes to be given to the winners!

I don't know what the rules for Double Dash will be. I'm not sure if I am going to attend, but I encourage all interested to get together and go! We had a few karters from NJ meet up at one of these for MK64 and it was a good time.

As much as I would love to fly to NJ from Vancouver, BC, I am lacking time and money