Palkia and Dialga already oppose him. Considering Giratina and the distortion world was created from inspiration of Anti-Matter (as they admitted in an interview, according to Bulbapedia), the real world is technically the opposite of Giratina.Well, depending on how you would like to interpret it, Arcues is just a "creator", and merely one Arcues that was born from an egg had created everything. Although we would interpret him as "God" that wouldn't necessarily make him the presider over things like Heaven. We may still get our "God" within the next generation since we need someone to oppose Giritina.
Well, on the right side of the screen is obviously a ledge (meaning those are being used, just like the other games). I see a dark patch in the bottom right, but it looks like dirt, just darker. On the very very right, it looks like stairs past the ledge. Maybe a ramp/slope that the bike can go up.Notice the black stuff that is just jutting out of the ground.
Or do you mean the boulders?