I have a near new bike only ridden a handful of times, it has a self extracting crankset I believe which uses a pin spanner, the drive side crank is now slightly moving side to side. This isn't happening on the non drive side crank, why is this? How do I tighten it and what tool do I need? See pictures below.
Chances are you tighten the crankset using an 8mm hex wrench. I'm not sure if any cranks take 10mm wrenches, but I believe most or all are 8mm.
I'm not sure exactly what the object with the pinholes does. On older self-extracting cranks that I'm familiar with (square taper or Shimano Octalink), the self-extractor had pinholes in it. When you undid the hex bolt that secured the crank, the bolt would push against the self-extractor and push the crank out. In that arrangement, the bolt was basically a captive bolt unless you took out the self extractor with a pin spanner. Speaking of that, a crank needs to be tightened down pretty hard - 40 Newton meters is a common spec I've heard, and it's quite hard, and it's definitely much more force than you could possibly exert with a pin spanner.
You do want to tighten down that crankset as soon as possible. If it's ridden loose, you could be stripping the splines on the crank that keep the spindle mated to the drive-side arm. If you rode a square taper crank with one side loose, after too long you'd deform the broached opening in the crankset (the square taper spindle was almost certainly steel, and if not that it was titanium, either of which are harder than the aluminum that cranks are made of, so it would be the crank that died). A prior answer alluded to that, but it was presumably deleted because this isn't a square taper crankset, and we can't be certain that this has happened yet anyway.