Here is Krok in his straight out of the box vanilla form.
It's partsformery, but super easy and completely reverse-able. Unscrew his rear croc legs from the inside of his bot legs. I put the screws back in so I wouldn't lose them. The screw can even be left in when we transform him back to beast mode. It adds a hair of height, but that's kinda needed with his rear legs.
From here we have two options.
Double reverse.
Take the two rear croc legs and move them to the reverse bot legs and slide them back on, having the beast legs fill in the hollow bot legs. The places where the beast legs slot/peg in still work. And you get this.
Single reverse.
Just pull the beast leg off, twist it a bit on the ball joint and slide it back on the same leg. Not quite as clean of a look.
The benefit here being the screw hole is farther back on the outside of the bot leg, but the beast leg doesn't fill the gap well enough and is a bit more awkward.
And that's it, A simple and reverse-able way to clean up the beast kibble from Skullsmasher or Krok.