Aside from the Cyberdark monsters themselves, Masked Dragon and Twin-Headed Behemoth are currently the strongest 2 Dragons that can be used with them (1400 and 1500 ATK respectively). Plus the Masked Dragon can search for itself and Twin-Headed Behemoth. After that, it depends on if you want to concentrate more on the Dragon aspect of the deck or the Machine aspect.
With the Dragon side, you can use Exploder Dragon (an attacking version of Exiled Force that is also 3 Stars so it can be used to raise the Cyberdarks) and tech in a Dragon's Mirror to bring out the Five-Headed Dragon.
With the Machine side, you can work towards bringing out Cyberdark Dragon (Overload Fusion would work here) as well as the standard Machine support cards (Limiter Remover, Cyber Dragon, etc.)
Future Fusion also is useful regardless which way you go since you can use it to get Dragons in the Graveyard or to help bring out Cyberdark Dragon (or Chimeratech Overdragon as well if you have that many Machines in the deck)
In Tactical Evolution, they get 2 boosts as well. 1 is a 3 Star, 1700ATK Dragon that's a Normal so Emissary of the Afterlife can find it and it can make the Cyberdarks have a 2500 ATK. Also they get a Fusion card called "Cyberdark Impact!" that lets you take Horn, Edge, and Keel from your Hand, Deck, and GY and shuffle them back into your deck to Fusion Summon Cyberdark Dragon (but these 2 cards are 3 months away).
But those are the core cards to look at for now.