Hi! Rain can be a very powerful archetype capable of overwhelming opposing teams in the right scenario. However, this team, I think, suffers from having a lot of sub-optimal sets as well as several pokemon like Politoed, Heliolisk, and Kecleon that are outclassed by other pokemon. Unfortunately, I'll be changing most of the pokemon on your team as a result, but I hope that these changes help you out in your battles! Also, I'll be making the team based on Smogon OU standards, as I don't know how Wi-Fi battling differs from that, so hopefully that'll still be good for these battles. Though if there's stuff like Primal Groudon running around, then the changes I'm about to make aren't going to work nearly as well. In fact, if that's the case, that would pretty much necessitate Primal Kyogre, plus I'd imagine a lot of the rain abusers that would be great in OU wouldn't be as good if stuff like Mega Rayquaza is around. With that said, though, let's get onto the rate.
With Pelipper getting the Drizzle ability in generation 7, it makes for a much better rain setter than Politoed due to its better movepool and typing. Pelipper gets moves like Roost for more reliable recovery than Rest, U-Turn for momentum-grabbing, and Defog to remove hazards. Its Flying type gives it some defensive capabilities that Politoed doesn't have like gaining a Ground immunity. As such, I suggest replacing Politoed with Pelipper.
Pelipper @ Damp Rock
Ability: Drizzle
EVs: 248 HP / 36 Def / 224 SpD
Bold Nature
- Scald
- U-turn
- Roost
- Defog
Moveset's pretty self-explanatory. U-Turn to pivot into your rain abusers like Mega Swampert and Greninja, Roost for recovery, Defog for removing hazards. The EV spread allows you to live a +2 Acrobatics from Hawlucha and a Supersonic Skystrike from Landorus-Therian as well as avoid a 2HKO from Choice Specs Keldeo's Hydro Pump.
Kecleon just doesn't fit here at all, to be frank. Competitively speaking, it's just not good compared to the plethora of other physical attackers out there. I'll use this opportunity to give the team some more defensive utility by replacing Kecleon with Ferrothorn.
Ferrothorn @ Leftovers
Ability: Iron Barbs
EVs: 252 HP / 24 Def / 232 SpD
IVs: 0 Spe
Sassy Nature
- Stealth Rock
- Leech Seed
- Gyro Ball
- Power Whip
Ferrothorn makes for a nice defensive glue for rain teams in general, providing a good water and fairy resist as well as being able to rack up chip damage on U-Turn users to wear them down. On top of that, it can set up hazards, which frees up the Stealth Rock slot on your Mega Swampert. The HP and SpD EVs ensure that Ferrothorn avoids a 3HKO from Choice Specs Greninja's Dark Pulse from full health with the rest being put into Defense.
Toxicroak is an interesting choice that's definitely not bad, but I'd like to add a different Fighting type that's been very successful on OU rain teams and has great potential as a late-game sweeper. That pokemon would be Hawlucha.
Hawlucha @ Electric Seed
Ability: Unburden
EVs: 96 HP / 252 Atk / 36 SpD / 124 Spe
Adamant Nature
- Acrobatics
- Swords Dance
- High Jump Kick
- Roost
Hawlucha has really great synergy with rain teams since it can set up on bulky Grass types that can take on your rain abusers and the rain abusers are great at wearing down pokemon that normally check Hawlucha such as Tapu Fini to the point where Hawlucha can take them on and pull off a late-game sweep. Hawlucha is typically paired with another pokemon that I'll get into next to set up Electric Terrain for Hawlucha to come in and use up its Electric Seed item, thus immediately granting it its Unburden ability, which doubles its speed when its item is used up. 96 HP EVs and 36 SpD EVs allows Hawlucha to survive a Moonblast from Clefable and 2HKO it with +2 Acrobatics. The rest is put into enough speed EVs to outspeed Sand Rush Excadrill in sand and max Attack EVs.
Heliolisk I think is outclassed by other Electric types that are more powerful and/or faster. As I just mentioned, Hawlucha and another pokemon pair very well together. That pokemon is Tapu Koko, which is much faster and is more powerful under Electric terrain. I think it's best to replace Heliolisk with Tapu Koko.
Tapu Koko @ Electrium Z
Ability: Electric Surge
EVs: 252 Atk / 4 Def / 252 Spe
Naive Nature
- Wild Charge
- Hidden Power Ice
- Taunt
- U-turn
As previously mentioned, Tapu Koko sets up Electric Terrain with its ability which activates the Electric Seed on Hawlucha. I think this particular set is good for this team because it can break through pokemon like Assault Vest Magearna and Chansey with terrain-boosted Gigavolt Havoc, which would normally want to switch into specially attacking variants and can also be problematic for rain teams depending on the team in question since Hawlucha and Greninja want AV Magearna weakened in order to KO it and Greninja also wants Chansey taken out so that it can't wall Greninja. Taunt helps it stallbreak even more, denying the use of recovery moves, status, hazard setting/removing, etc.
Now onto moveset changes!
As previously mentioned, with Stealth Rock now on Ferrothorn, Swampert gets a move slot freed up. I think that it should use Superpower over Stealth Rock in order to hit pokemon like Ferrothorn that want to try pivoting into Waterfall. In addition, I don't think Stone Edge is all that valuable on Mega Swampert. It can hit Pelipper in opposing rain matchups as well as hit Zapdos for damage without risking Static paralysis, but the team has other ways to deal with these pokemon, so I don't think it's important here. Instead, I think Swampert should be running Ice Punch over Stone Edge to hit other bulky Grass types like Tangrowth for super effective damage as they pivot in. A couple more minor changes is to move the 4 HP EVs to Def to give Swampert an odd HP stat which allows it to switch into Stealth Rock one extra time and change its nature to Damp since it has the added benefit of nullifying Explosion from pokemon like Landorus-Therian, which while pretty situational, is more useful than Torrent.
Finally, I think Greninja's better off as the Ash-Greninja set instead of Protean since the extra power from Ash-Greninja's insanely high Special Attack stat is incredibly good under rain and I don't think the coverage that Protean Greninja can get is that useful on this team since I think it's well enough equipped to deal with threats that Protean sets would normally run coverage moves for like Tapu Fini, Tapu Bulu, Toxapex, etc. Here's the set for it:
Greninja @ Choice Specs
Ability: Battle Bond
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Hydro Pump
- Dark Pulse
- Water Shuriken
- Spikes
Once again, fairly self-explanatory set. Hydro Pump and Dark Pulse for STAB, Water Shuriken for priority, and Spikes to hazard stack alongside Ferrothorn. Greninja forces a lot of switches, especially under rain, because of how strong it is so it can often use that opportunity to get up a layer of Spikes on a predicted switch which helps wear down the opponent's team if you can pressure the hazard remover(s) enough.
So this is honestly a pretty cookie-cutter OU rain team now, so apologies if you wanted something a bit less standard. I guess you could possibly keep Toxicroak and have your late-game cleaner be Shift Gear Magearna or something, which is also very commonly found on rain teams, but I think this should perform consistently well too, assuming you don't have a bunch of Ubers-tier pokemon running around, like I mentioned. In any case, you can always try it out on the OU ladder on Pokemon Showdown if you'd like. If you're not aware, it's a battling simulator that allows you to build teams and battle other players online without being restricted by what's available to you in-game. If you do try out that site, here's an importable that you can copy/paste into the teambuilder and be able to use the team immediately without having to manually put in everything.
Also here's a mock-up of what might work for a Toxicroak version of this team in case you like that more. Electric Terrain boosted Gigavolt Havoc from Magearna OHKO's Toxapex if timed properly, which otherwise walls Magearna. Just to mention some contrasts between the Toxicroak set you chose and the one I have, Gunk Shot is the better Poison move due to its base power, despite the lower accuracy. Drain Punch is preferred over Brick Break to regain HP. Pelipper is fine as the only rain setter so no need for Rain Dance on Toxicroak. Instead, Swords Dance can be used to help it break more defensive teams. Life Orb is the preferred item for Toxicroak because it really needs the damage boost it provides, as its Attack stat isn't all that great. Sucker Punch's best target is Mega Alakazam, which can give this team trouble since it has Focus Blast for Ferrothorn and the only other switch-in is Magearna, which you don't want to give too much unnecessary damage on generally. Also it can Trace Mega Swampert's Swift Swim ability, allowing it to outspeed Mega Swampert in rain, though it can't KO Swampert unless it has Energy Ball or uses Psychic in Psychic Terrain with some prior damage. If Mega Alakazam doesn't give you too much trouble, though, then I'd change it to Ice Punch so that you can hit potential switch-ins like defensive Landorus-Therian and Tornadus-Therian on a predicted switch with super-effective damage. I'm unsure of which one is better, honestly. Alakazam's not a huge problem necessarily if you keep your switch-ins healthy, but if you let them get weakened, it starts to be a big nuisance. Sucker Punch is probably the more forgiving choice if you're a beginner or someone who's still learning competitive pokemon. Much longer of a writeup than I was expecting for just an overview of an optional team suggestion, but there you have it lol.
