Countering Starmie
I thinks it's awesome that Starmie has managed to remain a strong part of OU throughout the years and while I do like Water-types a lot (like Misty the Starmie using gym-leader), here I'm talking about some reliable ways to take it out. Being a Psychic-type, it is vulnerable to being pursuit trapped or Sucker Punched, which, though it can be fixed a little with Reflect Type, uses a moveslot Starmie could be using for extra offensive pressure and will likely lose its STAB boost. Utility variants are most likely going to carry Scald, Rapid Spin, and MAYBE Psyshock if they do not carry Reflect Type for damaging moves. A Pokemon I would suggest for this type of Starmie would be Mega Sableye, which is a good Spinblocker and is immune to Psyshock. Mega Sableye can also KO with Shadow Ball. Other good options include bulky Water-types like Slowking, Manaphy, Jellicent, Azumarill, and Mega Gyarados. Grass types can really hinder Starmie too, like Ferrothorn, Celebi, and Assault Vest Tangrowth. Be wary of utility Starmie though, as it does have a passable amount of health, with reliable recovery in Recover and Leftovers and the ability to change its type. While it can't really touch you, it can passively hinder you with hazard removals and Scald burns. It even has Natural Cure to heal itself of status. As for the offensive variant, switching in on this is a DANGEROUS decision, with Analytic boosting the power of anything that dares to switch in. While they may carry Recover, the moveslot could also carry Rapid Spin. Offensive variants can chose from their decent movepool moves like Hydro Pump, Thunderbolt, Psychic, Psyshock, Ice Beam, or Hidden Power Fire. They also get Flash Cannon, Signal Beam, Dazzling Gleam, and Grass Knot, but they typically aren't as usable. Variants not carrying Psyshock can be dealt with with Chansey, variants not carrying HP Fire can be defeated with bulky Jirachi, and Mew and Calm Mind Clefable don't really mind anything a mainstream offensive Starmie throws at it, but though it's rarely seen, Starmie has access to Signal Beam and Flash Cannon as stated above, respectively. Also, typically things that outspeed offensive Starmie can usually check it without much of a problem due to Starmie's low bulk and typical lack of a Focus Sash, like Mega Manectric, Mega Sceptile, Weavile (which can also Pursuit Trap), Mega Lopunny, Scarfed Landorus-T, Scarfed Kyurem-B, Tornadus-T, Hawlucha, Mega Pidgeot, Mega Sharpedo (after a speed boost), Scarfed Hydreigon, and Gale Wings Talonflame, though if for whatever reason the offensive Starmie can live it, they are in critical danger of a Life Orb, Analytic, and (potentially) Super-effective and/or STAB attack coming their way. Starmie also HATES Pursuit-trappers like Weavile, Bisharp, Scizor, and Tyrannitar, as well as Sucker Punch from Nidoking (a definitely weird option but not out of the picture) and Bisharp. A lot of things nowadays can carry Knock Off, which doesn't help Starmie much either. Just focus on the low bulk while being wary of the drawbacks of not taking it out in one hit or not switching very carefully.