When I made my
S Rank Ralts nomination, I didn't even take Double Team that much into consideration at the time. I mostly got by most important boss fights with X Defend/Reflect and more importantly
X Speed use to pretty much stomp out most any boss that would prove troubling. Perhaps it's time I detail my Ralts' boss matchups in both versions in full.
Roxanne
Roxanne is obviously not a fight that Ralts can solo easily at all, but Ralts has the tools to considerably slow down Roxanne if your team is not equipped to deal with hers (such as underleveled/no starter or no Shroomish runs). A single Double Team can affect Roxanne's ability to hit you with her strongest attacks, allowing you to sneak in enough Growls to neuter her damage output and even potentially sneak in a few Confusions once you're done with that. This process is made easier if she spams Harden and Tackle as she often does. If you're really lucky, Oran Berry Ralts can even beat Nosepass 1v1, though I obviously wouldn't recommend going out of your way to do this.
Brawly
In my experiences, even an underleved Ralts (albeit not like 5-6 levels underleveled; Ralts can get more than enough experience to catch up via gym trainers) can solo vs Brawly without too much trouble. RS Brawly is easier since Makuhita doesn't have Vital Throw to threaten major damage, though Machop can potentially pose issues with Leer. Emerald Brawly needs to be handled with care, especially if Ralts had eaten a Seismic Toss from Machop beforehand. What you do is spam Growl vs Makuhita to constantly keep it at -1 or -2 Atk while negating its Bulk Ups and Confusion it down.
Volt-Ikazuchi even suggested the novel strategy of teaching Ralts the Thief TM to steal Makuhita's Sitrus and basically guarantee the one-mon sweep.
Rival2
You're not expected to get Kirlia and especially not Calm Mind by this point, so Ralts can't really go for any sweeping here. Ralts can attempt to set up Double Teams vs the rival's Wailmer (RS) & Fire-types (both versions) so you could at least do some lasting chip vs the rest of their Pokemon.
Wattson
Yeah this is rough; this can either be an easy-boosting session or a complete flop depending on how smart and/or lucky the AI decides to be that day. Synchronize + Cheri Berry helps significantly in setting up vs RS Wattson's Magnemite lead and should give you a decent avenue to overpower the rest of his team. Emerald Wattson's lead Voltorb is a lot riskier to set up on, but it may also potentially give you free setup turns by missing Rollout or even Selfdestruct lol. Emerald Electrike is a safer target to set up on, although you probably should kill it quick before it gets in too many Leers/Howls. Highly inconsistent, though
not impossible, which is still more than can be said for a lot of mons vs Wattson at this point.
Maxie/Archie (Mt. Chimney)
Archie is not a good matchup for non-Psychic Kirlia at any angle since even the Golbat can do a number vs you. Ruby Maxie isn't much better, but you may be able to squeeze a win vs Camerupt if the AI is dumb/unlucky enough. Emerald Maxie's Zubat can give you a window to Calm Mind sweep him.
Flannery
RS Flannery is basically free for Kirlia; even if you somehow don't have Psychic yet, you can easily build up to +4 Calm Minds (and even a couple of Double teams while you're at it) on the Slugma with a Super Potion or two, and wreck her from there. Emerald Flannery's lead Numel is not safe to set up on since Magnitude may fuk you up at a moment's notice, but you can still set up on her Slugma as well as her Camerupt (if your Kirlia is female).
Norman
Let me just preface this right now:
do not expect Kirlia to do much of anything vs RS Norman. If Slaking isn't pulverizing Kirlia turn 1 with Facade, it's disrupting your setup with Yawn or Faint Attack. RS Kirlia requires X Defends, X Speeds, and an unreasonable amount of luck and healing items to even hope to sweep RS Norman, though Gardevoir will have much less trouble accomplishing this feat. Getting Gardevoir at this point is not too unfeasible since the desert offers decent experience as well as a Rare Candy to give Kirlia the levels it needs, though this is such a detour that I don't count this as a plus for the matchup. Thankfully Emerald Norman is not as hellish of an experience for Kirlia since Spinda doesn't hit like a freight train, though Teeter Dance could still prove annoying, and you still need the X Defend, X Speeds and/or Double Teams, and healing items to expect a sweep. Easily Kirlia's worst matchup in the game, though the fact that it's still possible to sweep the fight as Kirlia speaks volumes to its potency.
Winona
Winona is pretty free for the most part, and you can even justify keeping Shock Wave for this fight since it can easily snipe her Double Team Swellow and Sand-Attack Skarmory if you choose to set up on those. Pelipper is the easiest target in this fight to set up Calm Minds on, but RS Swellow and Emerald Tropius are easy as well, and you could even try to sweep Emerald Winona immediately if her Swablu doesn't click Perish Song by the time you're done setting up.
Tate&Liza
RS Tate&Liza are kind of a joke in general to be honest since you can just double down the only real threat in Lunatone, and even if not Gardevoir can easily match Calm Minds, overpower Lunatone with Thunderbolts, and Blue Flute whenever it lands a Hypnosis. Emerald Tate&Liza requires more strategy but otherwise it's much the same in how you can just Calm Mind your way to victory; this time your main goal is to kill the Claydol fast before it gets to use Earthquake/Light Screen. Alternatively, Gardevoir could use Double Team or ideally
Reflect to slow down Claydol's (aka the entire team's only) attempts at hurting it.
Maxie/Archie (Magma Hideout & Seafloor Cavern)
These fights more or less play out the same so I'll just group these altogether. The Mightyena can no longer threaten you with damage since lol unSTAB Take Down, instead what you have to worry about are Scary Face and Roar, since Scary Face can let their ace outspeed you (though Sharpedo might outspeed you anyway), and Roar can end a Calm Mind sweep. If you don't feel like tussling with Mightyena t1, Gardevoir can resort to OHKOing Crobat and Sharpedo provided confusion doesn't get in the way (Persim Berry is appreciated here, and Tracing Crobat's Inner Focus is also nice for preventing Bite flinches), while Camerupt can still be 1v1ed.
Wallace/Juan
This is super free; all you have to do is use X Speed + Yellow Flute to ensure Luvdisc's Sweet Kiss doesn't interrupt your boosting and you can sweep from turn 1 with as little as 2 Calm Minds (though you ideally want ~4 Calm Minds for Juan to OHKO his Double Team Kingdra). This fight is even easier with a female Gardevoir since you can block Attract as well.
Sidney
Don't bother setting up on the Mightyena;
nothing sets up on Sidney's Mightyena effectively. However, the Shiftry is free pickings, so just X Speed once and max out Calm Minds to wipe out his team, hopefully without burning too much Thunderbolt PP when hitting his Double Team Shiftry. Cacturne may also get in the way of a clean sweep with Cotton Spore.
Phoebe
This is also really tough for Gardevoir to sweep, though this is the case for any Psychic-type not named Girafarig. Your best bets at sweeping are either hoping her lead Dusclops never clicks Curse as you set up 2 (or even 3) Calm Minds, or use Reflect + X Defend strats to try and set up on Sableye, though RS Phoebe's Sableye has Attract so again, female Gardevoir is ideal. That said, even if you do get Cursed by her lead Dusclops amidst your setup, you can at least try and take down about 3 of her mons before going down. I will not blame people for not using Gardevoir for this fight.
Glacia
Glacia is a pretty comfortable matchup for Gardevoir; Calm Minds can buffer against her lead Glacia pretty well especially if it wastes turns not attacking, and Sealeo can only annoy Gardevoir with Body Slam paralysis (though Synchronize can turn this into your advantage) or if it Encores your Calm Mind just as you're ready to OHKO everything on her team. If the Sealeo starts Ice Balling you should probably kill it quick before it literally snowballs. The only threat in this fight onwards is her Shadow Ball Glalie, but if you don't manage to already outspeed it naturally, set up an X Speed beforehand.
Drake
The Shelgon doesn't prove the easiest thing to set up on for Gardevoir since Double-Edge stings and Rock Tomb forces more X Speeds for a clean sweep. You can use either Double Team or Reflect to help ease the Double-Edge pressure as you boost up, and since Shelgon likes to spam Protect often, this shouldn't be too hard.
Steven
You could set up on the lead Skarm with Pecha Berry, but the ideal setup target in this fight would be Cradily, though be expected to expend some Full Restores to heal off Sludge Bomb poison. Much like Shelgon, resort to Double Team/Reflect to ease the pressure during setup. You absolutely need +6 to have a chance of OHKOing Metagross (don't be surprised if you do not), but even Claydol could potentially get in your way by tanking a +6 hit and setting up Light Screen, ruining your chances to beat Metagross. Again, tough but not impossible fight.
Wallace
Wailord should be easy enough to set up on (especially if you have Reflect), but you do want an X Speed so Tentacruel doesn't get to smack you with Sludge Bomb. The only other threat in this fight is Whiscash which could potentially slow you down with Amnesia + Full Restore should you fail to OHKO and hit back hard with Earthquake, but other than that it's smooth sailing.
