Access to Recover and a Psychic typing are both often synonyms of success in RBY. Starmie is no exception, shining in the oldest generation as one of the best defensive Pokemon, while still posing a threat offensively when Chansey is gone. Still, Starmie has even more things going for it. Starmie's great Speed lets it outspeed every OU Pokemon not named Alakazam or Jolteon, and provides it with one of the highest critical hit ratios. Starmie's movepool is also perfectly suited for it: in addition to STAB Surf, Hydro Pump, and Psychic, it also receives Blizzard and Thunderbolt, which make up the famous BoltBeam combination. In addition Furthermore, it learns Thunder Wave, one of the best moves in RBY.
Starmie is often compared to Alakazam, as both are fast Psychics with Recover, but Starmie has some specific defensive uses due to its movepool, higher Defense, and secondary Water typing. It is a much better check to Clamp Cloyster and Jynx, as well as Golem and Rhydon; in exchange, it loses coverage against Gengar, Jolteon, and Zapdos, and the ability to stay in against Chansey. Lastly, it's also worth noting that Starmie has the highest defense stats for a Recover or Softboiled user in RBY, which often comes in handy when dealing with physical attackers such as Tauros.
This is by far the most common Starmie moveset due to its great versatility. Blizzard hits Exeggutor, Zapdos, Golem, and Rhydon for super effective damage, and is also the most powerful move of the set to deal with neutral targets, such as Normal- and Psychic-types. The 10% freeze chance is never a bad thing either, and might prove game-deciding in on one of the many times Chansey will likely switch into Starmie. Thunderbolt, meanwhile, deals super effective damage to Water-types such as Starmie, Lapras, Slowbro, and Cloyster, all of which resist Blizzard. Thunder Wave can act as a deterrent to physical or mixed attackers such as Tauros, Snorlax, Persian, and various Electric-types. Be careful, however, as Chansey will often switch into Starmie, and a paralyzed Chansey could become more problematic than an unparalyzed one. Still, Thunder Wave is a great move to have for defensive purposes.
Thanks to its access to Recover and its typing, Starmie has multiple defensive uses. Like Alakazam, it can be a lead sleep absorber, as it can tank other moves from Exeggutor and Jynx, and also hit them before they can move. Blizzard can do heavy damage to Exeggutor and, with some luck—namely a critical hit or a few Sleep Powder misses—can put Starmie in a position where it can KO Exeggutor without being put to sleep. Starmie doesn't fare well against Gengar though, since Thunderbolt will 2HKO it.
Starmie can also be saved for the battle in order to make use of its great defensive coverage. If a teammate has already been put to sleep, Starmie can neutralize Exeggutor, which will find itself forced to use Explosion in order to take Starmie out, —and even that will not OHKO a full-health Starmie. Mega Drain Exeggutor might have a chance to KO paralyzed Starmie, but Exeggutor never packs Stun Spore and Mega Drain in the same moveset, so this only applies if Starmie has been previously paralyzed. Jynx will also get worn down by Starmie eventually, and will only succeed if Blizzard freezes it before, which one can expect to happen around one-third of the time assuming Jynx started at full health. A paralyzed Starmie is usually a hard counter to Jynx, though, unless Jynx is packing Seismic Toss and gets very lucky with full paralysis.
Starmie also makes an effective check to Golem and Rhydon, as it is able to switch into Earthquake and Recover off the damage while scaring them out with a super effective Blizzard. However, note that two high-roll Earthquakes from Rhydon will 2HKO Starmie, while Starmie can't OHKO in return without a Water-type attack. Meanwhile, Golem has a chance to OHKO Starmie with Explosion; Starmie won't like the occasional paralysis from Body Slam either.Team Options & Additional Comments >>>
Surf and Hydro Pump are STAB options that increase Starmie's power against neutral targets such as Normal-types, Alakazam, and Jynx. Surf, especially, makes Starmie an even better Golem and Rhydon check, as it will OHKO them. In order to use any of these two moves, you should choose between forgoing Thunder Wave's support or dropping Blizzard. Doing the latter means losing super effective coverage against Exeggutor. Starmie will still be able to wall it, but Exeggutor will now have plenty of time to paralyze Starmie, fish for Special falls, set up Explosion, or even replenish its health with Mega Drain as you while Starmie tries to stall it out with Recover. While Surf is the most consistent and common option, Hydro Pump can 2HKO Tauros and will 3HKO Snorlax and Alakazam. As an example, Surf increases Starmie's chances of beating Alakazam one-on-one, sometimes after Alakazam gets fully paralyzed twice in a row. Hydro Pump's fewer PP makes this more difficult, but its ability to 3HKO Alakazam might let Starmie beat a paralyzed one switching into a Hydro Pump after a critical hit or a full paralysis without taking a Thunder Wave in the process. Surf is commonly used over Blizzard while Hydro Pump is usually used along with BoltBeam for a more dedicated sweeper.
Ice Beam is the general Ice-type alternative move to Blizzard, but it's generally an inferior choice on Starmie. Ice Beam's main selling point is its higher PP, which is useful for freeze wars, but Starmie can't stay in against Thunderbolt Chansey anyway. Although Ice Beam could actually be useful for Alakazam and Thunderbolt-less Chansey stall wars, Blizzard is usually Starmie's strongest move, so the inferior power will often be significant when using Ice Beam instead. Psychic is another attacking option sometimes used on Starmie leads to 2HKO Gengar. Psychic's ability to hit Victreebel super effectively is also noteworthy if you are planning to drop Blizzard for it. However, unlike Surf and Hydro Pump, Psychic only hits Alakazam, Jynx, and Hypno for resisted damage. Psychic's main disadvantage is arguably that it only 3HKOes Golem and Rhydon. Compared to Surf, Psychic has 5 less Base Power and 8 fewer PP, but boasts a 30% chance of scoring a Special fall. Hyper Beam is the only move in Starmie's movepool that might bother Chansey, and might come in handy against Alakazam as well. Hyper Beam does 35-41% to it, which means that Starmie could surprise a weakened (<50%) Chansey attempting to switch in on it. In addition, in desperate situations, a critical hit Hyper Beam can do up to 80% to Chansey and sometimes OHKO Alakazam. Hyper Beam is a very situational move though.
Starmie can learn both Reflect and Light Screen, but neither is particularly useful on it. Light Screen won't prevent Chansey from countering Starmie, although it can help against Slowbro. Regarding Reflect, Starmie is going to be met with Chansey (or Alakazam) almost every time it comes in. Even if the opposing physical attacker stays in, you should probably just attack, because once you set up Reflect, your opponent will go straight away to Chansey, so you have likely just exchanged half a Body Slam, with its 30% paralysis chance, for 0 damage in return. Reflect is only useful when the opponent is only left with physical sweepers, when it could admittedly make a difference.
Checks and Counters
Chansey is by far the safest Starmie counter, as it takes pitiful damage from Starmie's attacks and threatens Starmie with paralysis and a likely-to-2HKO Thunderbolt, and can even use Softboiled whenever necessary. Chansey only has to worry about Blizzard's 10% freeze chance (only 9% factoring in accuracy) as it switches in, but if Chansey is paralyzed, Starmie becomes completely worthless against it: Chansey can simply paralyze Starmie and fire off Thunderbolt until Starmie gets fully paralyzed or Chansey scores a winning critical hit. Alakazam can generally shrug off Starmie's attacks with Recover, but a Starmie packing Surf might be more problematic. Alakazam is also susceptible to being frozen but the threat of paralysis is generally enough to scare Starmie away; Starmie can't handle Alakazam's Seismic Tosses well either.
The two Electric-types, Zapdos and Jolteon, can abuse Starmie's weakness to Electric-type attacks with their STAB Thunderbolts. Jolteon is generally a better Starmie check than Zapdos, as it can outspeed Starmie and isn't weak to Blizzard. Neither of the two will enjoy being paralyzed by Thunder Wave though. Victreebel and Venusaur can hit Starmie super effectively with STAB Razor Leaf, but Starmie also hits them for super effective damage in return with Blizzard or Psychic, and Starmie is faster than both of the two Grass-types.
Paralysis provides a great way to weaken Starmie and make it less effective, both offensively and defensively. Stun Spore Exeggutor and Thunder Wave Slowbro will sometimes end up hitting Starmie, while Body Slams might paralyze it as well, depending on which Pokemon your opponent sends Starmie into. Exploding on Starmie with Exeggutor or Snorlax can work in a pinch, while Cloyster and Golem can sometimes lure Starmie in and Explode on it in the switch in, but this is riskier.