From 4e4, a Knight can go to 24 different places: 4d6, 5e6, 4f6, 3e6; 2e5, 2f4, 2e3, 2d4; so on.
In Mixed 3D Chess, each square is potentially attacked by as many as 4 Pawns, and therefore Pawn weaknesses are not quite as pressing. After, for example, 1. 4e4 N4g8-4f6 2. 4e4-4e5 N4f6-4d7 3. 4e5-4e6? Black can capture any of 3 ways, and though the Pawn at 4e7 is a bit blocked there are other e-Pawns that can be moved to get the pieces developed, and of course Black still can attack 4e5 with a Pawn -- in fact, with any of 2 Pawns.
However, Pawns still have very limited mobility, which was designed so that Pawn chains can still be formed and play their normal part in setting up walls that make the strategic terrain more interesting. The weaknesses on both sides normally caused by a Pawn chain will sometimes be absent.
For example, after 1. 4e4 4e6 2. 4d4 4d5 3. 4e5 4c5 4. 4c3 4c4, we have a perfect 2D Pawn chain. Black's 4th move here is probably wrong, but is played to set up the example.
Moving into the third dimension, 5. 5e4 defends 4e5 with a second Pawn, and reveals that a 3D Pawn "chain" is shaped more like a mountain than like a wall.