I'm no expert, but let's see what we can do.
Good setter. One thing is that it has nothing to hit Steel types, which is a minor issue since Corviknight and Gholdengo run the meta. I would recommend Mystical Fire and Psychic instead of Calm Mind and Stored Power. Also, if you want, you could make it really stupidly bulky and give it Sitrus Berry, or go for Life Orb to gain some big hurting prowess. Other than that,
First up, we got the EVs. Since it has a massive HP stat, it can go uninvested and still be fine. Instead, go all in for Attack and Special Defense. For the remaining EVs, give it to Defense. For the moves, Ice Punch is great for bulky Ground types that Hands has trouble breaking past otherwise. My only other nag is about Wild Charge. (Edit: im an idiot and forgor to capitalize)>Recoil is not great on a Pokemon that you don't want to take a ton of chip damage from. I would replace it Thunder Punch, which has less power, but you stay alive for longer.
As much as I like the set, the item could be better. Dark and Steel only hit a select few for super effective damage, and those who you do hit super effectively will most likely be dead without an Expert Belt, like Gholdengo and Dragapult. If you want a spicy style Kingambit, I've used a Choice Band a couple times. If you want more of a tank, you can go for Assault Vest. Also, the ability might be better as Defiant. Change it if you want, if not, Supreme Overlord is a great ability for it, but it's a bit more effective in singles.
I can tell only by the four moves that you are doing some serious hurting with this set. Minor complaint, I ran leftovers on a couple of my teams until I was informed that due to the faster pacing of doubles, Sitrus Berry is often better.
Wow. Screen Support and Trick Room? He has it all! Again, the only thing is about the item. Heavy Duty Boots aren't necessary as hazards aren't a huge thing in doubles. I would use either Light Clay or Sitrus Berry for long lasting screens or healing alike. I'm a little conflicted on the ability. I love the prospect of two Berries for him, but I also don't want Kingambit to hurt your team with Sucker Punch. Other than that, good set.
Appletun is meant as a bulky special attacker, but 100 Special attack isn't going to end well uninvested. For the new EVs, I would recommend 168 HP/252 SpA/92 SpD. Other than that, the set is good.
This is a certified extra spicy Trick Room team. The biggest problem with most of the Pokemon are their items. I will admit, I was very surprised by the Appletun, so you've got that going for you. I only left the Appletun alone because I know how it feels to use a cool-looking Grass type that's middling at best (Arbolivia). Other than that, that's all I got for you.