Not only is the stage bad (in competitive play) because of camping,
SmashWiki defines camping as "the act of moving to and staying in an isolated, safe place, such as the far corner of a stage, to evade opponents." What might camping involve? From the same site:
- Using a spammable projectile, which can also be done to force the opponent to approach.
- Charging a special move.
- Deliberately letting time run out, to win via stock/percent/point lead.
- Waiting for the opponent to approach, usually done with percent or stock lead.
- In free-for-alls, waiting until the opponents have sustained more damage.
- Stalling.
We can ignore FFAs and stalling, since the former is not in competitive play, and the latter has no intent of actually fighting. It's pretty unfair to treat spamming as only being performed by projectiles because a lot of characters spam the same attacks, regardless of it being a projectile or not. Still, who has projectiles? Well, I think we can actually think of who is campy. A lot would probably accuse Samus of being spammy, hence the name "Spamus". Characters who may be notorious for spamming projectiles are Duck Hunt, Greninja, Link, Mega Man, Olimar, Pikachu, R.O.B., Robin, Toon Link, and Villager.
Other, less "offensive" spammers include Bowser Jr., Corrin, Dark Pit, Diddy Kong, Dr. Mario, Falco, Fox, King Dedede, Lucario, Lucas, Luigi, Mario, Mewtwo, Mii Gunner, Mr. Game & Watch, Ness, Pac-Man, Palutena, Peach, Pit, Ryu, Sheik, Wii Fit Trainer, and Yoshi. That's 35 characters I can think of with projectiles that aren't restricted like Bowser's and Charizard's. That's 60% of the roster that can and probably already does spam projectiles. So, by your words, this percentage makes Sm4sh a bad game because these characters can camp. If you wanted to throw Bayonetta and Cloud in there, that's 64%. (Bayonetta's n-air, which has been used as a way to chip damage.)
What about charging a special move? Some characters need space to do that. By "charging", I'm not going to include someone like Diddy Kong, who needs to charge his Rocketbarrel Boost because that's more of a recovery than it is an attack. Peanut Popgun can be charged as well, but letting go of neutral B will release it. So, what I have in mind here are chargeable specials that can be charged without having to hold any button. This would include characters like Cloud, Donkey Kong, Kirby, Lucario, Mario, Mewtwo, Mii Gunner, Pac-Man, R.O.B., Robin, Samus, Sheik. I included Kirby, since he can copy a few characters with chargeable specials. That's 21%.
The other two on that list are similar, but this can be performed by anyone and is usually performed if the timer is running short. I don't think anyone wants to see a match go for its full six minutes, but it happens. Usually, when it does, people tend to get excited because it becomes a game of trying to see who can outlast who. The one character who receives most of the blame for this is Sonic. Of course, Pac-Man can pull the same stunt. I wanted to show you how many characters can be campy and that camping is a legitimate strategy. You don't have to like it, but to think it makes a game bad in the competitive scene might make you wonder why anyone is even playing Sm4sh at all.
but the tree also leads to some jank,
I heard that the biggest problem with the tree is that anyone who tries to attack the opponent standing on the tree could end up losing because of some OoS attack. There is a way around this. Two ways, actually. The first would be by limiting the duration one can be on that tree. It takes 400 frames for Limit to charge. That's the longest charge any character has in Sm4sh. So, since 400 frames is 6.667 seconds, make the longest duration anyone could have to be up there, 7 seconds. Not that anyone would need that much time to charge anything in such a large stage. The second would be by playing on it as an omega stage. No tree, no ducks, no dog. Honestly, if "some jank" is the problem, then
Lylat Cruise is a problem. But, then why not just make Lylat Cruise an omega as well? Lylat Cruise's blast zone also alters based on the way the ship is turning, so . . .
as do the ducks (staling/blocking projectiles).
There is a reason why "counter-picking" exists. It doesn't make sense for someone to get upset or want to make a stage illegal, all because some poor character won. The irony about blocking projectiles is that Duck Hunt was a good stage for Samus. I don't know about you, but ducks never became a problem for me whenever I went to that stage.
The dog is another element that may not be RNG but can still be pretty janky, even top players don't always know when the dog is going to show up
Nor did some dog. Top players not always knowing where the dog is going to show up is their problem. If you're top player, but cannot be cognizant as to where the last duck that was killed ended up dropping, then maybe you're not a top player. Sure, the dog could show up anywhere if a duck isn't hit, but something tells me that's not as much of a problem as people make it out to be.