OmegaShoutmon is not the same OmniShoutmon from everywhere else. Due to the alternate universe in which Shoutmon has actual digivolutions, each one both fitting two specific things; Music, and eventually becoming King, as the Xros Wars Shoutmon's initial goal was to become. OmegaShoutmon is redesigned to incorporate the "Rocker Arm", which is an arm designed after an Electric Guitar, which can be used as such to emit hyper powered sonic waves from the stereos on it's back, which can send even the heaviest of Digimon flying backwards, and is also capable of flight with this method, literally surpassing the speed of sound while rocking out to the sound of the wind around himself.
OmegaShoutmon is a redesigned version of the official OmniShoutmon to suit the evolution line of Shoutmon's Ultimate Form. While Arresterdramon otherwise is unchanged, OmegaShoutmon is modified to better fit in with both it's prior and next stage.