I'll be totally honest, I thought this would be dead easy to do, since I already have an extremely successful Mega Swampert team. My original plan was to just swap out my weird set for your Cropert set....but then I read that you wanted sandless. As you can imagine that made my idea crumble xD. Anyways, this is what I was able to come up with.
The drive behind this was to lean towards a more bulky/HO Ground Build. Not using the best Lead/Defensive Wall on Ground nor the Best Sweeper in the game was pretty tough, especially since I was forced to use a (very) underwhelming Mega. Your Swampert is really the only "defensive switchin" on this team, and I say that with quotes because there are some pretty bulky mons on the team.
Swampert was the Mega of choice, with great bulk, a nice neutrality to Water, and relative ease to set up/an attack that has very little Pokemon that are actually immune to it, so 8 times out of 10, after a few Curses or so Waterfall will always pack a good enough punch.
Next, I added Mamoswine, whose naturally an awesome partner for Swampert, since it helps tremendously vs Grass and Dragon, as well as has access to amazing priority. I wanted to try something different here, and try out Freeze Dry Mamoswine. It's really fun, since it can 2KO both Rotom-Wash (if Physically Defensive) and Slowbro.
104 SpA Life Orb Mamoswine Freeze-Dry vs. 248 HP / 8 SpD Rotom-W: 159-190 (52.4 - 62.7%) -- 99.6% chance to 2HKO after Leftovers recovery
112 SpA Life Orb Mamoswine Freeze-Dry vs. 252 HP / 0 SpD Slowbro: 205-244 (52 - 61.9%) -- 98% chance to 2HKO after Leftovers recovery
I was working very hard on his Evs to get the highest possible chance to 2KO both of these after leftovers recovery, and have enough speed to outpace Adamant Breloom and Bisharp. For the last slot, I used Superpower so you 2KO Chansey, and do a pretty good chunk of damage to P2 (plus, Krook has Knock Off, so I don't see much of a need for Mamo to have it as well).
Krookodile was (eventually) the lead I decided on. What's nice about it is it can function as an anti lead as well, and Intimidate (which really helps with the lack of a Physically Defensive Wall on the team). From there, the set's pretty basic.
It took me a little while to decide on who I wanted as a Scarfer, but, after some thinking I popped on Torterra. Despite the fact that he's pretty slow, its just enough to outspeed Keldeo, and any non Scarfed non Swift Swim Water Pokemon below Starmie, which is good enough for me! Wood Harmer hits tremendouly hard, and helps graciously against (as I said a second ago) Water, and Ground mirrors. Stone Edge is for that nice Rock Coverage, and allows it to hit Flying and Fire mons super effectively. Crunch was decided on over Superpower for additional coverage against Psychic, and I didn't like the fact that its locked into Superpower (especially since its not banded), and you're usually stuck having to switch it out afterwards. If you'd like though, Seed Bomb you can also pop on here if you're not crazy about Wood Hammer's recoil damage.
Zygarde's another underrated mon, but, trust me, he's a great late game cleaner! He gives us a third neutrality to Water, and a good check to Mega Charizard Y (whose especially threatening w/o Sand to hopefully lock it into Solar Beam). After a Dragon Dance or 2, without Ice Shard its gonna be pretty hard to stop this guy, especially since its pretty bulky, which makes it a lot more reliable.
I was desperately lacking a Special Attacker on the team, so, for the last slot I resorted to Landorus. With Sheer Force + LO, it's absurdly strong, and with its part Flying Typing, you have a 3rd Grass Neutrality (Along with Torterra and Zygarde), and a resistance to Fighting Attacks (especially w/o Excadrill/Hippo, Fighting is a bit of a rough matchup for this team). This is also why I have Psychic over Sludge Wave. Calm Mind allows it to easy break through even the peskiest of wall after 1 or 2 boosts. and makes it much more threatening.
