I forgot who referred to D&D when speaking about zoning (and too lazy to look back in the thread,) but I'd like to expand on that. I believe my analogy would be most related to that concept (again, not sure, never played D&D to be honest.)
Zoning with Samus is a matter of control, or rather her dominion. For example, take a chessboard out. The ultimate goal would be to threaten and trap the king. We can translate this to knocking the opponent off the stage. However, the secondary goal would be to take as many pieces of the opponent's as possible without losing your own to make the primary goal easier. We can translate this into Samus damaging the opponent without taking damage . And in order to do this, control must be established. And one of the early rules of chess is to control the center (ironically, this is a rule in Smash as well.)
Control can be established two ways: A) actual presence of the area or B) exercising sovereignty by having a pre-determined answer to anything that enters that dominion. Let's use BF as our chess board (arguably Samus's best stage and I will explain why soon.)
Samus can establish control with option A with her usage of z-air as a vanguard and push her way to the center. Or, the more popular option B, establish control with projectiles. You could view her usage of z-air and super missile as a rook, creating a threat horizontally. More importantly however, you can view her usage of her homing missile/z-air as a rook and bishop, creating a threat horizontally and diagonally. Again, looking at a chess board, this means if Samus were placed at B4/B5 on say BF, she establishes control over the entire 4/5 row and control over the upper diagonal.
Why is this important? Because through this analogy, it can be concluded that Samus’s best zones are in fact created through an opponent's diagonal approaches. When opponents attempt to go through her projectiles, they will either go straight through air dodging/shield dashing which then is up to the Samus player to be read and punish with the proper tools (grab/pivot grab/backwards shz-air/f-air or simply retreat with bomb)… or jump and approach diagonally. On stages such as SV and FD, this can somtimes be problem.
Why is it not a problem on BF? Because platforms get in the way, which later opens windows to u-air, u-tilt and f-air, that platform protection makes all the difference. Notice how all her combo starters intiate from N/NE/NW (depending on which way you're facing) and end either N to S. Meanwhile, most characters aerials d-airs never hit diagonally (SW/SE). Essentially, this is what it looks like:
(C1) (C2) (C3)
(S) (XX) (C4)
This is Samus's dominion. C4 can be controlled easily, but any projectiles beyond C4 can be dodged/shielded and just plain avoided. C3 can still be controlled via sh-homing and z-air. C1 can be controlled with screw attack. Finally, C2 can somewhat be controlled with all aerials and projectiles (minus d-air). Samus dominates even better in the C2 region when there's a platform protecting her.
It is the XX region where Samus is weakest. This is because of her natural weakness in short-range fighting as well as the natural strengths of her common opponents: D3's chain grab, MK's dashes and sh-aerials (where they're not quite high enough to be in the C2 region yet make the exception with a long diagonal hitbox to his d-air) and Falco's boxing game. Notice also how Marth will be trouble at times because Marth lies both within the C4 region and the XX region, his sword still being able to reach you even when your ground attacks cannot.
Also notice how when Samus players do not play on BF or platform stages in general, their lack of control over the C2 region furthermore allows opponents to access the XX region. And from there, your options become severely limited.
Now that we've analyze the proper zones for Samus (this can and should be applied against all characters,) spacing is the next issue. As Samus, you must essentially space yourself so your opponent stays either outside this box or within your dominion. NOT WITHIN (XX.)
Doing this will make or break your game.
That's as far as zoning goes. If you want to discuss what to do in region XX, a.k.a. Samus's options when in short range, that should be discussed separately. As for when Samus is above the opponent, the objective should be to land asap. The only exception would be if there were (oh how ironic) a platform. Then your options differ.
As we all know, zoning also pre-determines the efficiency of characters in certain stages. With the zones for Samus established earlier, the best neutrals would have to be BF and Lylat. Lylat, while not always having a straight horizontal terrain, nonetheless gives Samus exactly what she needs to zone properly. FD, while being straight and clear, gives too many opponents easy outs to her projectile game. SV is similar... and Yoshi's, while having a platform... also has a horrible horizontal terrain with a horrible tilting platform on top of that.
While I'm sure many of us play like this, I'm sure there are a number who do not actually realize that this is practically the strategy that dominates their gameplay style, albeit subconsciously. Therefore, I hope I've helped in illustrating that.
