NoCheese , that is awesome. I look forward to seeing how it turns out! I love the Mega Slowbro + Chansey combo. You have a very good read on the threats to the team. I would definitely consider giving Chansey enough speed to outspeed Walrein4, as nothing else on your team manages it particularly well (and I wouldn't be afraid to attempt to set up Dragonite, knowing it might be sacrificed to bring Chansey in safely). As you identified, Substitute is definitely the way to go with Chansey on this team.
Don't be afraid to just kill Taunt users; while having a Pokémon set up is awesome, it's not always strictly necessary, particularly with Pokémon that are as good at switching in as Slowbro, Chansey, and Dragonite. I'm not really convinced that Mega Slowbro and Chansey aren't better at muscling through Taunt than Suicune; Mega Slowbro has much higher Special Attack, after all.
The "Natural Cure problem" is a big annoyance, though; I viewed Aegislash's Poison immunity as somewhat critical to my team's success. Fortunately, Slowbro's Fire and Ice resists make it a good deal easier to switch in to moves that induce burn/freeze, then switch back out against Ghost-type moves from the likes of Froslass/Glaceon.
I'm not sure why you're particularly worried about Curse users; I'd think Slowbro could switch in on them as soon as they come in and set up an Iron Defense, tanking the boosted hit easily (+2 Garchomp4 EQ does under 50% max to 252/252+ Mega Slowbro). Haxorus4, on the other hand, seems like a massive annoyance, with Dragon Tail preventing Mega Slowbro from walling its boosted attacks. But by and large, I think you could lean on Mega Slowbro pretty hard for physical attacks; even Lickilicky4's Explosion can't do 50%, and Electivire4's Thunder Punch can only manage 35% (but the switch-in sucks, and you may need to make a sacrifice). The most dangerous physical threat is Tyrantrum4's Head Smash, which CAN do over 50%, but even that can't win if you sacrifice Dragonite to bring Slowbro in, go Mega, Iron Defense, and Rest.
I would probably make a fair number of willing sacrifices playing this team, and most of the time, it would probably be Dragonite. The free switch-in to Mega Slowbro against physical attackers and Chansey against special attackers/OHKO users seems well worth it. I wouldn't be too scared of Mega Slowbro ending up burned or poisoned, since it should beat any switch-in that lacks a phasing move or a OHKO move anyway, thanks to the insane defense boosts.
Good luck!
As you play more you'll get a better idea of when Chansey's Sub is due to break, so you can give special attackers just 2-3 chances to drop Special Defense or status if you're particularly concerned about it (not that you won't get trolled by something critting to break the sub and then paralyzing Chansey with the last Thunderbolt PP when you've got +6 Evasion). Also if Chansey KOs the lead with a Sub and maxed evasion, there isn't a special attacker that could come out second and capitalize on the -1 or -2 Sp. Def (well other than Clawitzer, but hopefully you'd switch to Slowbro and set up).
Chansey just needs a backup Toxic absorber, a Fighting resist, and a hard hitter in the lead position to deter opposing lead boosters and Perish Song users, and fortunately quite a few Pokemon can do two or more of those things. Dragonite seems like it's just kinda there as a good Pokemon that can occasionally make battles much shorter, and you'll definitely miss having passive recovery somewhere on the team against Taunt users; I dare say that a TrickScarfer could make for a very effective lead, with the idea being that you'd be Tricking or switching out much more often than trying to KO the lead outright.
I'll also note that this kind of Chansey with speed to outrun Walrein (oops, read Wailord as Walrein. Walrein is a little faster and requires 124 Speed EVs) can admirably fulfill the Whimsicott/Sableye role on a Durant team while also being a backup sweeper. Just lead with Durant (you can make it slower and more defensive to better handle leads like Medicham, Mienshao, and Machamp because Chansey can come in on Fire moves from Scarf Manectric, Garchomp, and Entei) and switch Chansey in on all those Protect/Detect/Fake Out/Explosion users that can't do too much damage to it.
Thanks for the suggestions, guys! I've played the team more now, testing out a few changes with respect to Chansey, and I've been very satisfied.
First, as you note, having Chansey outrun Walrein is absolutely, positively essential for this team, and embarrassingly, I assumed that Wailord was faster and that Walrein was already covered. Whoops! Thankfully, I fixed that before Walrein fixed me!
Second, the more I've played, the more I want even more Speed on Chansey. When Chansey outruns its foe, everything is on easy mode. No more tracking damage to predict when the Substitute will break, no worries about a status attack, Leech Seed, or stat dropper slipping through, and no more having to burn through Substitute's PP on moves that will break the substitute if they hit but likely won't hit due to Minimize. Most notably, and expanding on the Substitute PP issue, going first means that a previously set-up Chansey is much more reliable against physical attackers. When I go first, I can merely re-Sub when the Sub is broken, not have to guess when my evasion boosts will fail, and otherwise merrily attack and Soft Boiled. So long as the foe doesn't string together a whole ton of hits in a row, Chansey should win. When I go second against a powerful physical attacker, I'm stuck in a bad situation, since I either have to predict a hit and Sub ahead of time, lest my Substitute be broken and Chansey ends up exposed to a strong physical hit the next turn, or just try to force through damage quickly and hope my Seismic Tosses kill before two hits land in a row. Oftentimes, of course, Seismic Toss will win this race, but against foes that can heal or the like, this is much dicier. And even if I just need to stall out one or two particularly threatening moves, pre-emptive Subing rapidly drains Substitute's PP, which can again invite awkward situations.
Accordingly, I did a bit more breeding, and for the past 100 battles or so, I've been using !!Timid!! Chansey, with a spread of 4 / 0 / 244 / 4 / 4 / 252, for stats of 326 / 17 / 56 (84) / 56 / 126 (189) / 112. For comparison, Bold 86 Speed, 252 Def Chansey has 15 more HP and 9 more (post-Eviolite) Defense.
I've been EXTREMELY impressed with this spread. Basically, the extra HP from a bulkier spread is worth very little to something with such huge HP, especially when I'm already committed to decent Speed investment to beat Walrein, while the 10% loss in Defense is easily outweighed by how much easier a time I have against foes, even physical ones, that Chansey now outruns.
And let me tell you, there are a lot of foes between 86 and 112 Speed. While I obviously won't directly switch a Chansey in on a physical attacker in this range, a previously set up Chansey can stay in and win against tons of them. This isn't a huge issue when things are going well (after all, there's always Slowbro!) but unusual situations, mistakes, sloppy play, bad luck and the like can happen, so I feel much happier having a Chansey that's both easier to play (going first makes things easier even against foes where Chansey wins when slower) and more reliable in handling threats it otherwise might not be able to. Take a scan through the Speed tiers list, and consider how much easier many of those foes are when Chansey outspeeds them. No more risk of Roserade slipping in a Leech Seed or Toxic, no more awkward Substitute spamming games with Articuno2, lest you let up and have it land two Sheer Colds in a row, etc. Honestly, the Speed investment has so impressed me that I'm very tempted to experiment with faster spreads on my old reliable Substitute Suicune.
While I currently believe that Timid Chansey with GG Unit's moveset is the best fit for this team, I also did, for comparison, some experimentation with Timid Blissey and a set of Substitute / Calm Mind / Soft Boiled / Ice Beam.
With the loss of Eviolite, you lose a bunch of Physical bulk, and some Special Bulk compared to Chansey. This is compounded by the loss of Minimize, which removes the ability to even pseudo-boost Chansey's Defense, meaning that you lean much more heavily on Slowbro for handling physical attackers. But you do at least get some reasonable compensation for the sacrifice.
First, you get to use Leftovers. Leftovers recovery makes up most of the initial loss in Special bulk, and makes Substitute games go a bit faster, as you don't need to Soft Boiled as often. Second, your ability to boost your Special Bulk even further is much more reliable than the pseudo-boosting of Minimize. Aura Sphere is no longer as much of an irritant. Third, you are a little faster than Chansey, and so gain the advantages of going first against more things. Fourth, Ice Beam does not make contact, so you avoid Flame Body / Static complications.
Additionally, and likely most importantly, Blissey needs to stall out far fewer things, and Blissey battles tend to go much faster. Blissey's SpA is nothing amazing, but unlike Chansey's, it is usable, and at +6, Blissey's Ice Beam can 2HKO a ton of stuff. This means Blissey can smash through many foes that heal themselves while Chansey is stuck in stall mode. Similarly, nothing is immune to Ice Beam, so Ghost-types (with certain exceptions like Chandelure) no longer doom Blissey to a massive stall-off. This is important because Growl-less Chansey doesn't actually have that many PP available, and lacking Pressure and the PP stalling beauty of Rest, stalling multiple foes can be tough. Even fully set up, Seismic Toss Chansey often has to stall or partially stall multiple foes out, and when a couple Ghost-types appear on a foe's team, this can be irksome. Blissey can also power through Perish Song Mismagius, which Chansey doesn't like at all.
Obviously (and I often use this in my battles) Chansey can frequently conserve its PP for potential future use by stalling out a foe's relevant moves and then switching to Dragonite or Slowbro to set up and start sweeping, so the issue of PP and my dislike of lengthy stalls is more an issue of time/convenience rather than a massive team weakness, but there is definitely value in being able to play faster. Also, in a related note, Chansey's immunity to Ghost-type attacks is a real mixed blessing. Yes, avoiding the risk of Special Defense drops from Shadow Ball is delightful, but sadly, the immunity also slows the stalling process. Neither Dragonite nor Mega Slowbro like taking repeated Shadow Balls, so until a foe uses up Shadow Ball's PP, I have to leave Chansey in to stall. Were Shadow Ball merely not very effective on Chansey, foes would use it up rapidly, letting me switch to Dragonite or Slowbro and set up pretty quickly, but since it's completely ineffective, foes typically wait to use it, and I have to burn a lot more time stalling Ghost-types out. Blissey can often avoid this problem, since it can actually hurt Ghost-types.
Finally, the decent power of +6 Ice Beam also means that previously set-up Blissey still beats a number of Physical attackers by simply 2HKOing them while they break its sub. This all said, I still feel that Chansey is the better and more reliable choice, but if you hate frequent mega stalls, Blissey is indeed quite playable.
A few notes on my lead: Dragonite could quite likely be improved upon (and a Trick-Scarfer lead certainly is tempting), but I appreciate Dragonite's ability to speed battles up and muscle through stuff that can cause complications for Chansey and Slowbro. I certainly am very willing to sacrifice and semi-sacrifice Dragonite against certain foes, but I'm not constantly playing for a sacrifice, since with such great walls on each end of the spectrum in reserve, it's very rare I get punished for killing something with Dragonite (and maintaining the option to sacrifice it later) instead of making an immediate sacrifice and set up. In other words, it's extremely unlikely that by not sacrificing Dragonite, I'll lose my only chance to set up during the battle. A couple of relevant examples. Against Walrein, I do what I did on my old Dragonite / Mega Metagross / Suicune team, and semi-sacrifice Dragonite by trying to Dragon Dance twice, then attack. If the Sheer Colds miss, I have a healthy Dragonite at +2 that can rip through most opposition. If either of them hits, no worries, I can freely set up Chansey, and retain the option to switch to and set up Slowbro after the OHKO moves' PP are used up. Against lead Tyrantrum, I just Outrage and OHKO it, rather than sacking to set up Slowbro.
On the subject of sacrifices, however, you are completely correct that it is very important to be aware that even with their massive bulk, switching into certain attacks and eating a crit can be dangerous for Chansey and Slowbro, so when I have any sort of doubt, I attack or set up with Dragonite, since the worst case scenario is a free-switch in and a safe set up. I strongly believe that it's much easier to lose with this team by switching Chansey or Slowbro in too aggressively than by leaving Dragonite in when it should be switched out, and thankfully, this aligns well with the fact that the fastest, easiest battles are those where Dragonite is able to just set-up and sweep.
I've rambled for a bit, but I'm loving the team, so thanks again for introducing me to Chansey and providing helpful comments on my initial spreads and builds!
EDIT: cleaned up some typos
