Now I just played some For Glory myself, and I must admit, I was met with some spam. It's not that I couldn't handle it, it's the fact that for some characters it is very effective. Even playing some 1v1 with my friends, it is just too easy to stand on one side of the stage, and have a strong, hard to punish, game. It doesn't help that everyone (except for Little Mac) has insane vertical recovery, making it hard to keep them off the stage anyways.
Here are my main culprits:
Bowser Jr: The Mecha Koopas, and cannonballs. The mechakoopas apply pressure, and yes you can grab them, but with just a little bit of lag it's hard to do, and Jr can get the easy punish if you get caught. The cannonballs have insane priority, which bothers me as a Diddy player in Brawl where bananas had similarly high priority. But the difference here, is that in Brawl, most projectiles had decent priority, and they all got nerfed coming to Sm4sh. So many projectiles trade with other projectiles, like they should be, but the cannonball trumps all. This wouldn't be hard to handle in most cases except for the fact that there's no platforms. This makes his ground projectiles way too safe for comfort, and it's just really hard to deal with.
Villager: The tree, and the Lloid Rocket. This isn't had bad offensively, but defensively, it's pretty strong. The tree blocks most, if not all projectiles (haven't done much testing, but I've never had an easy time getting through it) and if you just set it up and hide between it and the side of the stage, it's a very safe position. Because again, NO platforms! There's no simple way to get over the tree, jumping is super telegraphed, and you can't wait for him to come at you because he has Lloid rockets that he'll just keep spamming. Although they don't have the highest priority, and he has to come out in front of the tree to use them, you cannot break it until it starts flying, and the window to both break the rocket AND get to Villager before he's behind the tree is very small.
Close range characters (yes, most of them): Shielding and dodging (mainly rolling). I've faced too many people where as soon as we both get close to eachother, it's just lots of rolling. No one is even getting punished, it's just nothing. Sure we're trying to play safe, but it's sad because it works for the most part. I don't have any facts, and maybe it's partial lag, but I feel like the window between each roll is noticeably small. Neither of us want to attack because most attacks are very easy to punish. I don't remember this happening a lot in Brawl or Melee (definitely not Melee), but the games really feel like you just need to fish for easy punishes, because it's frankly very easy in this game. Playing aggressively is a tough thing to do, and with the lack of room for big combos, it's not as rewarding as playing safe.
The close range spamming (Little Mac, and others mentioned) is easily beaten by shielding, and dodging, or just good zoning, but the ranged spamming is a bit too strong for certain characters imo. I'm not even saying this as someone who's losing a lot. But frankly, with my friends explicitly saying, "I'm not happy with you right now," to each other is not cool. Leave this drama to Mario Party, not the "balanced" For Glory mode. It leaves a bad taste in your mouth, it's sad because it works so well. And what's worse is that it's easy to telegraph, I see all their moves coming, and it was just too bothersome that any approaches to get around the projectiles were easy to punish. I was playing Rosalina against a Fox, and now it was in my favor, I'd just throw out Luma, a good distance away, he'd jump, try to hit me, I shield, throw off stage. Easiest thing to do. Or if I had Luma in my possession it was too easy to catch him landing, or at certain ranges, he'd see me shoot it, so he'd just jump, and again, easy punish.
The game is still very young, so who knows how I'll feel with more play, but at the moment, I found that this camping and spamming strategy is a bit too strong on these flat stages. And it's dumb because the entire competitive scene knows that FD isn't a fair stage in many matchups, Nintendo just took the, "No items, Final Destination, Fox only," meme a bit too seriously.