The following is based on a 1-1-1-1 gunner, since the area I play in does not allow customs. This means that I have medium range zoning tools, in the form of Forward Air and Flame Pillar, with Charge Shot the only thing in my arsenal that is long range.
Some general stage-specifics for a 1-1-1-1 gunner: Stages that allow for Stage-Spikes to occur are the best stages for most circumstances, as it gives another kill opportunity for a 1-1-1-1 gunner. The projectile from the up-B can stage spike if timed correctly, though on the flip side, it also allows others with stage spike potential the ability to kill the gunner.
Stages that allow recoveries through the stage (Such as Halberd) are generally worse, due to the fact I rely on the incredibly potent Flame Pillar as an edge guard to set up hard-read punishes, as well as the stage preventing stage spikes.
Final Destination: I personally find Final Destination to be the best stage for myself to play on, with the exception of specific matchups. The large amount of horizontal space allows the gunner to give up space gradually, giving them more chances to deal with an approach before they run out of space. The lack of platforms preventing an opponent from taking a platform-assisted approach. The only characters I would not take to Final Destination are those who out-zone a 1-1-1-1 gunner, namely Villager and Duck Hunt Duo.
Town and City: A good substitute for Final Destination. It isn't as wide as FD, but a third of the time the stage's platforms are too high to be of use for approaches though make it harder to follow up on opponents after kicking them up, a third of the time the stage is FD, and a third of the time it has platforms that are actually usable. I treat this stage as a backup FD, though with some alterations for some characters who have high enough jumps to make use of the top platforms. Greninja comes to mind.
Smashville: An average stage for 1-1-1-1 Gunner. The stage is particularly narrow, which lowers chances for zoning, and the platform allows enemies to approach and recover to, which ruins Flame-Pillar edge guards, though on the flip side, allows for charge-shot punishes if you expect them to land on it off stage for an easy kill. Overall, I don't find it to be the worst stage, but I would still prefer FD.
Battlefield: I rarely go to Battlefield. The narrow stage makes it harder to zone out characters, coupled with the platforms makes it easier for enemies to approach and follow up, while making it harder for the 1-1-1-1 gunner to get footing back on the ground. Moreover, characters who thrive on such close encounters usually have good stage spike potential, so not only is it easier for them to get the 1-1-1-1 gunner off the stage, it is also easier for them to land the kill. The only exception would be to take Duck Hunt Duo here but there are better stages for that.
Duck Hunt: A very wide stage, giving the gunner good space to do what they do best. The birds can be a problem with projectiles used off the ground and the vertical walls on the side of the stage prevent stage spikes. Overall, this stage is an alternate FD. I don't take this stage against Duck Hunt Duo or Villager, due to the fact they would out-zone me. I also no longer take this stage against Shulk, because he can camp the tree with Jump while he waits for his other Monado Arts to cool down, even with the Gunner's massive up-air range.
Castle Siege: A mediocre stage. The first transformation makes it easy for enemies to approach, due to the narrow size and platform locations. Camping the top right is easier than the bottom left though, using Forward Air to cover jumps and Flame Pillar to cover ground approaches down the slant. The second transformation, while the statues block projectiles, also extends how long forward smash lasts, which can catch people out. It is also nice and spacious and can allow for some easy walk-off kills with down smash. The final transformation is just a worse version of FD, due to the tilt dictating when projectiles are useful and when they are not. Overall, I take this stage to counter Duck Hunt Duo and Villager.
Delfino Plaza: I don't particularly have much to say about this stage. Most of the stage is similar to Battlefield, except the enemy can recover underneath the stage. The transformations allow for quick kills off the side blast zone with down smash, most transformations are also very hard to approach, making them good zoning spots. The transformations also prevent spikes and gimps. I pick this stage against characters who have trouble killing without spikes and gimps, such as Shiek.
Halberd: This stage is possibly the biggest double-edged sword for 1-1-1-1 gunner, all thanks to the low ceiling. This allows the 1-1-1-1 gunner to kill earlier with down-tilt, however I rarely find myself dying off the side blast zones as 1-1-1-1 gunner, which means the low ceiling reduces my lifespan drastically. The slight tilts can screw up Flame Pillar and Forward Air, and the central platform can give opponents a very easy to use, readily available approach option. Overall, I heavily avoid this stage against characters who can kill off the top of the stage easily, such as Captain Falcon or Little Mac, and I take it against characters who are impossible to keep off-stage or gimp, such as Villager and Rob, possibly even Duck Hunt Duo for earlier kills against him.
Kongo Jungle: The slants make it hard for the 1-1-1-1 gunner to use flame pillar and forward air effectively, and the platforms make it harder for the 1-1-1-1 gunner to follow up on opponents after tossing them into the air. Coupled with the narrow stage, it allows opponents very easy approaches. The barrel also allows opponents to recover easily, though the saving grace of this stage is that so can the gunner. Keeping track of where that barrel is at all times has saved me many times on this otherwise dismal stage.
Lylat Cruise: No. The slant makes flame-pillars on the edge impossible to use, which flat out removes an edge-guarding option. The stage is very narrow, which makes enemy approaches easy, doubly so with the platforms. The tilting stage makes effectiveness of projectiles more or less random. Overall, this stage has all the wrong elements that harm the 1-1-1-1 gunner greatly. The only exception is Ness, due to the impossibly hard to grab edges causing him to suicide.
Tldr; Wider stages are the best stages for the 1-1-1-1 gunner in most circumstances.
