Ben 10 The Rise of Hex

This is easiest on level one.

You want to spend most of your time as the robot crab-looking guy. I tried this a couple of times as the big swamp monster guy and I always got shot. Don't rush, use your RS to peek ahead before you drop down and spam some shots as you move forward and you should be fine. You don't have to defeat all the enemies so you don't need to fight the red guy below the exit unless you fall. If you are the robot crab, he'll shoot right over you though, so it's not a big deal if you fall down to him.

The key, though, is definitely to use the robot crab. Playing mostly as him, the ach was total cake.

I found this extremely easy to do with Big Chill, or whatever, the blue guy that has ice attacks and can double jump and glide. Just use the Y dash attack through any enemies to freeze them, use the double jump to sequence break (like when you need to activate a bunch of platforms to get the green keycard, just head all the way to the right, drop down the ladders, activate the machine with the crab guy and climb back up and double jump onto the platforms). I had to use the red double jump guy to grab the red keycard, but you can do it without actually solving that room's "puzzle" if you do that.

Very, very easy and takes about a minute to zip through the level.