This will NEVER fully replace the official wiki. The creation of this "guide" (and the uselessness of the pro tips) just shows that Kong people on ROTMG have no common sense.
Best way to kill a void eater- While it's charging up it's gravitational beam, (It seems like it's drawing black circles into itself) get behind it. Once it fires, you'll be drawn towards the BACK of the void eater, where it is most vulnerable, and can be killed with a single swing. Best way to kill a gray- Wait for it to shoot its lance. You have to hit it WHILE it's shooting its lance, otherwise it'll just harden up. Do this three times to destroy it.
If you combined this with Super Paper Mario, you would have a game that sells billions. Even a game that a team of professionals worked on doesn't have the depth of this game!