For the ditto I'd just like to say this: Don't fastfall onto another laser below you if you can avoid it, and don't jump into high lasers. You can win the laser game by simply paying attention to the heights the opponent is firing at while shooting your own against so many Falcos.
For Peach, the float height just above SH laser max height can be hit with uair and fair, if she's floating and you can't just hit her for it but her position is threatening, you should just get out of there immediately, preferably with a roll or wavedash or other movement that maximizes distance between you and where she's projected to land if she were to start falling. You can also catch her descent from a float with lasers anyway if you have room to move back at all. Feel free to just start uptilting and back airing her if she was airborne, get some quick percent. Dash attack can clank favorably with any tilt, but ftilt reaches the furthest to allow you to deal with the most possible approaches at once, though the knockback isn't great at lower percents. It's big enough to avoid whiffing and losing to down-tilt, however. As soon as it begins knocking down, uptilting over and over is your version of downsmashing a peach who CCs, but you can stop it prematurely or continue it further based on their behavior changing. Spacing bairs or landing another strong aerial into a combo of some sort to make more of your neutral options safe vs CC is a must.
Fox. Don't get shined OoS, avoid getting shined (or grabbed) in general, and don't DI shines up near the ledge. Avoid letting him hit you with fullhop approaches or fullhop counter approaches. Just don't have predictable movement and stop jumping around when he jumps, unless you're fullhopping to whiff punish or intercept his fullhop. Your dash dance may be limited, but it can adequately punish approaches targeted towards your current position. Your throw combo game is truer and better on Fox than any other fast-faller by no small margin. Certain floaties and middle fall-speed characters may have more trouble with say, bthrow or up throw (and fthrow can even CG certain characters, but no Fox under any circumstance). Fox is also the character you're most likely to get a combo off of if you shine-grab but hit with the shine and whiff the grab. Fox directly approaching your aerial hitboxes tends to be difficult, but he can dash dance around them or use running shield. Retreating AC bair is much harder to do this kind of thing to, and with most Foxes trying to run in and grab the endlag they're probably not going to actually reach you before you can escape, and you'll often be able to get a move of your own out. Be vigilant for roll->shine or uptilt. If you aren't attacking, you should be able to bair, dair, or uptilt this if they were going to end up close to you in the first place.
Marth. Everything is less safe on shield, including high retreating aerials because his grab reaches so high. He can't regrab DI behind at 0 in the CG, and he can't tech-chase DI all the way behind tech away off of dthrow without a hard commitment (pre-emptively wavedashing) and that won't even always work. Jabs aren't great, but can catch close dash dances, and can force royzones on moves like fsmash and grab. If you can get him into position, fair and uair lead to crazy damage, and he's one of the best character to do pillar combos to. You can often sneak under aerials he comes down with with a dash attack. Laser->aerial isn't really safe vs anyone, but Marth is one of the easier characters to punish this with an aerial oos with. Laser->ftilt or even laser (possible pivot) fsmash can work in these scenarios to punish such an attempt. Ftilt can be faired OoS, but ftilt can beat dtilt's range too. You can beat most of his ground approaches and combo off of them with dair, but if he uses extreme range like ftilt or fsmash he can get around this. Run up shield can destroy aerial walls, many forms of nair intercepting or approaching, and even dtilt if you get in on the range. SH bair can also beat sh AC nair and a bunch of other approaches he might try. Most of Marth's moves have more start up than those of other top tiers, so trying you move in closer with hitboxes to stop the startup isn't bad, it's just you can get grabbed off of a weak hit even if you do this successfully. Don't get dash-dance grabbed or uptilted.
Sheik. CC and quick action out of shield destroy a number of unsafe things Sheiks love to do, including just about any rising aerial if you can move correctly (also all her tilts, her jab, unspaced aerials dsmash). Space to not be in shield grab range to force nair out of shield or non-retaliatory options. CC fsmash vs ledgehop fair can mean Sheik is dead ridiculously early. Bair is amazing, as is dtilt. Feel free to grab her a lot just for positioning, as Sheik probably wants to get a grab on you somehow, and spacing in place could get run-up shield grabbed. Don't get grabbed or gimped.
Puff. Laser-> ground move is extremely effective if she's low airborne. Don't get wavedash back grabbed. Back throw and fthrow combo into things. If puff doesn't or isn't drifting away and goes for an aerial on shield, bair oos and nair oos can work. Otherwise avoid having to shield in the first place. Reposition a little and laser, or bair. Bair to intercept her coming in. Dtilt is amazing.
