Did some more experimentation recently--
Played around with all the Neutral-Bs; Neutral-B1 is easily the most versatile; it's a solid KO move and doesn't take much time to charge up to a useful state; doing a shorthop away and charging it can bait opponents into moving forward or attacking, and even if they don't, its great speed, variable and instant start-up (the same reason a Lucario charging Aura Sphere is so hard to approach), and mix-ups with the steering (turning in the opposite direction takes away the hitbox until you start moving in the opposite direction; you can pass through the opponent and give yourself a good bit of space so that OoS tools wouldn't hit before you barrel toward them again; you can also hit a shield and turn immediately afterward) make it a low-risk, moderate-reward tool. It also has the advantage of more than doubling Jigglypuff's general movement, making it a good option for punishing techs, since "roll backward" is something that Jigglypuff struggles to fight against. Going for half-charge is useful because they don't require you to turn if you whiff (with a full charge, you'd otherwise keep going and die), and the variance also makes it much harder for opponents to get used to a specific punish timing. This move is better than originally thought; use it more, customs or not.
Relentless Rollout (Neutral-B2) grows in speed faster than regular Rollout in terms of movement speed and can therefore take advantage of the steering mix-ups mentioned earlier more easily, but you don't really get much out of them, since the damage is pitiful. It allows you to use it at very low percents without it being punishable on hit. The fast charge and ability to go through opponents she hits give Jigglypuff another recovery option, but that point is likely negligible since her recovery is excellent regardless. The biggest blow to its viability is its lengthy animation; no matter how little you charge it, you will be spinning for a while, even if you don't have an active hitbox with zero charge. This makes it more predictable than regular Rollout and easier to punish even with its extra speed. Low damage means that the opponent risks much less by testing their luck with a swing, too, so it appears to be a moderate-risk move with rather low reward. It doesn't drag Luma, either, so unless there's a matchup that we really need the extra help recovering, I don't think it's worth using.
Raging Rollout (Neutral-B3) is an interesting case, as it has a significant start-up time (you have to charge it for about a full second before it starts hitting while in motion) and cannot be steered. However, it is also unshieldable, has fast movement speed, is quite powerful even with only a moderate charge, and ends much more quickly; even if you can't steer, you're only about two double-jumps away from easily getting back to the ledge when you miss, and that's assuming you're, like, in the center of Battlefield doing it with a considerable charge; it can be even safer depending on distance from the ledge and amount of charge. This allows you high flexibility in your recovery on a whiff despite being forced offstage, and the fact that it's unshieldable and powerful makes it much more likely that opponents will not try to challenge it. It is unlikely that this move will hit anyone reliably in 1v1, but it's likely good for shaving time off the clock since people really won't want to mess with you while you do it. That said, regular Rollout seems rather good at that because of its much faster charge time, greater variation in speed, and the ability to steer it, so it's hard to justify this as a reason to use it in Singles. In Doubles, though, this move should be excellent, as it can be charged behind a partner and released on reaction to anyone hitting your partner near the ground for massive damage and knockback on a super-speedy hitbox that cannot be shielded and is difficult to punish on whiff.
Pound is a nice, versatile move with a lot going for it. The start-up is decent, allows you to continue "steering" up to when the hitbox comes out, and has a big, long-lasting hitbox that doesn't get weaker over time. Its solid speed and big hitbox makes it relatively easy to tag shields with, and it does about 60% of a full shield's health, which can be a game-changer if you can keep on the pressure. The lingering hitbox often catches opponents off-guard at mid-range, too; it's not very unsafe to use just outside of an opponent's range. Does good damage and puts them above you, letting you pressure with your aerials on a hit. A great stand-alone option that does a lot for her range and shield pressure. Probably the best of her Forward-Bs overall.
Sideways Pound (Forward-B2)'s worse start-up (in comparison to regular Pound), small/less lingering hitbox, and general inability to distinguish itself much from her standard edgeguarding fare make it a pretty poor pick overall. Yes, it sends people at a 20-degree angle, but it's very hard to land, is relatively easy to punish on whiff, and is harder to follow-up on. It does have a niche in sending Luma about half a Battlefield's distance away even without prior damage, but the other two Pounds are already useful in that matchup and do more than that. Hard to recommend over the other two.
Pound Blitz (Forward-B3) seems to be a solid alternative to regular Pound. The start-up is very significant (first active hitbox is Frame 25 intead of Pound's 13 or Sideways Pound's 18), but there are a lot of aspects that mitigate that (admittedly rather large) liability. Since you can still steer Jigglypuff until the hitbox is out, you have new baiting flexibility in that you can Forward-B and start moving backward during the start-up, especially since it causes Jigglypuff to move forward more than Pound does. It is relatively safe on shield (in terms of safety, shielding Pound Blitz is similar to shielding the late part of regular Pound), and the final hit sends opponents straight up (as compared to regular Pound's 75-degree angle), which works well in tandem with Leaping Rest and U-Air as compared to F-Air/N-Air/Forward-B (yes, Pound -> Pound) pressure with regular Pound. The greater horizontal movement also assists with recovery ever so slightly. This will likely be more useful in specific matchups and is definitely not simply inferior to regular Pound.
Played around with all the Neutral-Bs; Neutral-B1 is easily the most versatile; it's a solid KO move and doesn't take much time to charge up to a useful state; doing a shorthop away and charging it can bait opponents into moving forward or attacking, and even if they don't, its great speed, variable and instant start-up (the same reason a Lucario charging Aura Sphere is so hard to approach), and mix-ups with the steering (turning in the opposite direction takes away the hitbox until you start moving in the opposite direction; you can pass through the opponent and give yourself a good bit of space so that OoS tools wouldn't hit before you barrel toward them again; you can also hit a shield and turn immediately afterward) make it a low-risk, moderate-reward tool. It also has the advantage of more than doubling Jigglypuff's general movement, making it a good option for punishing techs, since "roll backward" is something that Jigglypuff struggles to fight against. Going for half-charge is useful because they don't require you to turn if you whiff (with a full charge, you'd otherwise keep going and die), and the variance also makes it much harder for opponents to get used to a specific punish timing. This move is better than originally thought; use it more, customs or not.
Relentless Rollout (Neutral-B2) grows in speed faster than regular Rollout in terms of movement speed and can therefore take advantage of the steering mix-ups mentioned earlier more easily, but you don't really get much out of them, since the damage is pitiful. It allows you to use it at very low percents without it being punishable on hit. The fast charge and ability to go through opponents she hits give Jigglypuff another recovery option, but that point is likely negligible since her recovery is excellent regardless. The biggest blow to its viability is its lengthy animation; no matter how little you charge it, you will be spinning for a while, even if you don't have an active hitbox with zero charge. This makes it more predictable than regular Rollout and easier to punish even with its extra speed. Low damage means that the opponent risks much less by testing their luck with a swing, too, so it appears to be a moderate-risk move with rather low reward. It doesn't drag Luma, either, so unless there's a matchup that we really need the extra help recovering, I don't think it's worth using.
Raging Rollout (Neutral-B3) is an interesting case, as it has a significant start-up time (you have to charge it for about a full second before it starts hitting while in motion) and cannot be steered. However, it is also unshieldable, has fast movement speed, is quite powerful even with only a moderate charge, and ends much more quickly; even if you can't steer, you're only about two double-jumps away from easily getting back to the ledge when you miss, and that's assuming you're, like, in the center of Battlefield doing it with a considerable charge; it can be even safer depending on distance from the ledge and amount of charge. This allows you high flexibility in your recovery on a whiff despite being forced offstage, and the fact that it's unshieldable and powerful makes it much more likely that opponents will not try to challenge it. It is unlikely that this move will hit anyone reliably in 1v1, but it's likely good for shaving time off the clock since people really won't want to mess with you while you do it. That said, regular Rollout seems rather good at that because of its much faster charge time, greater variation in speed, and the ability to steer it, so it's hard to justify this as a reason to use it in Singles. In Doubles, though, this move should be excellent, as it can be charged behind a partner and released on reaction to anyone hitting your partner near the ground for massive damage and knockback on a super-speedy hitbox that cannot be shielded and is difficult to punish on whiff.
Leaping Rest (Down-B2)'s great movement speed gives Jigglypuff a nice tool for threatening the space immediately above her; U-Air has a decent hitbox, but her slow vertical speed and stubby limbs leave much to be desired in terms of scaring opponents who are immediately above her. This move fixes that issue and can sometimes scare opponents into a preemptive airdodge, letting you punish the endlag relatively easily. Much like regular Rest, it is affected by Rage a significant amount, so Training Mode testing doesn't do it justice in terms of its KO power, and while it isn't as powerful as regular Rest, the very beginning of Leaping Rest is still pretty powerful (more powerful than the upward hit) with many of the same properties as regular Rest (invincible Frame 1, active Frame 2, opponent punishes with whatever they want on whiff). Opponents who are generally too safe or elusive to reliably use Rest often find this move to be a pain; it's a high-risk, high-reward option that can be significantly more applicable than regular Rest in some matchups. Would you trade some of the obscene power of Rest (KOing at 25-50% before the hit, depending on Rage) for extra juggle utility and range? I think it's an interesting question, and one that will probably be up to personal preference and matchups instead of one obviously being superior to the other.
I can think of literally zero use for Wakie Wakie (Down-B3) in competitive play. I suppose the logic is that it's a Down-B without significant endlag while the start-up windbox attempts to push others away, but with such abysmal start-up leading to a very short-lived hitbox, any use of that is likely going to be confined to free-for-all, as even in Doubles you're much better off using the other two Down-Bs.
tl;dr--1X2X, with Forward-B being between 1 and 3 and Down-B being between 1 and 2. One set dedicated to vs. Bowser/Yoshi for Spinphony actually getting better against their armor; standard Rest works well against them and regular Pound works well against them (1131, and/or 1132 for Leaping Rest's utility). Those six should cover everything. If you really need more sets, the last four would likely go toward Doubles (Raging Rollout with other stuff). If it's Singles-centric, I'd take a poll on what appears to be the less useful stuff so that people will be placated (I know people will want Sing...ugh).
1121
1122
1131
1132
1321
1322
Doubles stuff--
2121
2122
2321
2322