The Dragon Two is nearly a perfect match for DJ Player, with feature sets matching each other great! The only drawback I've found so far being the need for a powered USB hub to let iOS use it.

This mapping gives a full 4 deck mapping with a few deviances from the labeling on the controller.

Button - Function (S+ prefix = Shift + button)
CUP - Tap Tempo
S+CUP - Jump to start
Scratch On - Slip mode on/off
S+Scratch On - Tempo Range
S+(Monitor)Cue - Key Lock

The FX section needs a bit of experimentation/explaining:
(The following is for Deck A or C, depending on which is active. For Deck B or D, replace S1 & S2 with S3 and S4, and P1 & P2 with P3 & P4)
S1 - FX1 On
S2 - FX2 On
Push P2 - FX3 On
Push P1 - Fader FX On (Let's volume fader control main parameter of all FX turned on)
P1 - FX1 Main parameter
S+P1 - FX1 Secondary parameter
P2 - FX2 Main parameter
S+P2 - FX2 Secondary parameter

From above, if you want to control the FX3 main parameter, turn FX3 on and then enable Fader FX.

When switching the Dragon Two over to 2 Deck mode (not the DJ Player mode, the physical switch on the Dragon Two) you lose the full middle section as it turns into an actual analog mixer and disables MIDI for those controls. As such you do lose Fader FX and Key Lock from the controller. One way to retain similar control as the Fader FX is to remap it to Jog FX and control it using the jog wheel instead.

A recommended setup is to use this mapping in 2 Deck mode on both the Dragon Two and DJ Player, and then using the touch screen on the iOS device for controlling effects.