Won 100 arcade mode levels – This is actually really easy if you do it right. What you need is 2 controls first. Go to Act 1 Wrenchworks from your S.H.I.E.L.D access point. Use Ms. Marvel and Invisible woman and get to the very end of the level. Skip all the guys and just get to the very end. Right before you exit the level, load up the second controller and put it on arcade mode. Use Ms. Marvels ranged move and kill a few guys with the first player controller. Usually 2-4 is fine. Once you’ve done that, exit to the omega exterior and there’s your first arcade win. Rinse and repeat and you should be done in no time. I don’t have this achievement yet and the only people who I know who have it don’t know if you can turn off your console and continue. So please be careful when you do this because if your 360 stalls like mine did (at 40 arcade wins), you might have to restart all over again from 0.
It should take around 30-60 seconds per arcade win.
Tron Edit: You ARE able to turn off your xbox and continue later. Either the next day or four months from now.