Dealing with Cloudy weather? Longish post incoming.
Ditto to the get him offstage and tap him. I'm biased and say bring Megaman, because Cloud's recovery is so predictable, and dear god do you have options for edgeguarding him. Lemons, Flame Sword, Slash Claw if you're ballsy, standing there with Leaf Shield if you want since he doesn't snap to the ledge, and of course Hard Knuckle for the spike. You can also use Flame Blast with proper timing. That sort of edgeguard does rely on him popping above the ledge a little, though Hard Knuckle is always applicable, as is just walking off the ledge with Leaf Shield active after holding it for a second.
From personal experience, though, I find Samus is fun for dealing with Cloud if you're aware of his movement. I find that anyone facing a Samus tends to get airhappy, especially when they've got the advantage in aerial attack range. It makes baiting them in to Charge Shot kills very easy, and Cloud players' love of Limit Breaks gives you all the time you need to prepare them. I haven't had much luck with getting him in the air outside of Samus' fair seemingly being faster than Cloud's fair. His dair outpaces your uair, though you should both get hit once pretty often. Similar to Cloud dittos, Cloud's uair outpaces your dair as Samus - in fact, Cloud's uair seems to outpace most dairs. Your best bet is usually gonna be to dodge it.
On the flipside, do not Dorf unless you've got someone you can bait. I'm not the best touchstone for this, but my experience is all I have to offer, and I have never Dorf'd a Cloud that was even remotely intelligent. The smart ones keep that sword in my way & aren't dumb enough to approach much. His recovery will hit you if you try to utilt him out of it very often because he doesn't snap to the ledge, and he simply has better range and speed than you do. His recovery is better than yours vertically, but not horizontally, so you can abuse that with a Fair or Dair if you get him offstage. That, however, is true of all characters to a point: abusing Cloud off-stage has led me to win at 30% damage with no stocks lost.
I do not suggest Cloud Ditto unless you're confident you play a better Cloud than they do, though I think that goes for most dittos. If you do try it though, remember that Uair hits before Dair - if they get you up, airdodging past is your best bet if they give chase. There's a gap before his fsmash hits, even uncharged - enough time to shield, but do not roll away. The number of times I've been caught by the third hit because I rolled on instinct is ridiculous. That shit kills.
Do not try to abuse Final Touch, it's not that great. Yes, it can kill very early, but it requires a near point-blank hit and comes out slower than it looks. Don't underestimate the Limit Break version of his recovery, either, that shit hurts. Remember that at very low percents you can airdodge the second hit of his recovery if he's trying that on you.
On the flipside, if your opponent is trying to kill with Final Touch, you can abuse that readily. They have to get in quite close to pull it off, so a simple airdodge or shield will get you out of it, and his cooldown is long enough for a quick punish.
Some Clouds are gonna pretend they're Mario and go for a grab above all else. If they land it, they're going to dthrow you and turn around for a side special. Don't let them follow up if at all possible.
...Most of this sounds like a rambling mess to me, but I typed too much to just close it out. I hope at least some of it helps. I also apologize for the limited character experience - I bought this game for Megaman and have picked up Samus, Dorf, and Cloud, and am working on adding Marth and Captain Falcon to the list. Can't say as I feel like a terribly versatile fighter.
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