In the midst of complaints of nobody wanting to talk about the game, I've also been thinking about Jolteon recently.
I feel like Pin Missile Lead and Rest Back Jolteon can be divided into two different pokemon, basically.
Lead Jolteon with T-Wave, Thunderbolt, Double Kick and Pin Missile is very hard to wall out - when you get a favorable matchup on say Starmie lead, and they swap on twave or stay on tbolt, you start the game off very strong, threatening to crit through stuff, and generally score lots of damage on sleeping threats. However, there's three main caveats to Lead Jolteon. 1: Rhydon. Normally, you justify a rhydon weakness by running Zapdos who's a big monster that kills everything, but Jolteon's measurably less destructive. Speaking just on lead here, I like how Lead Jolteon has better clicks vs Alakazam and Starmie - leading zapdos vs starmie and twaving on blizz and then tbolting as they swap happens a lot and isnt really ideal...God forbid starmie freeze or crit. Zapdos in lead just has less consistent clicks, but the point remains. There's a rhydon weakness, and are you really gaining enough upside?
The second critique is that it can mess with your sleep game, like outlined by Believer of GXE. Alakazam lead teams frequently spread twave and attacks early though, and they get by, using normal moves on their Exeggutor to push sleep through early, or just keeping sleep for the late game. It's not a particularly unworkable caveat, but it's something to keep in mind with Lead Jolteon.
The third is that it often twaves at lead and has Snorlax enter on it, and just beat it out. Once Jolt has to swap out, it loses a lot of threat, and you see a Jolt just get manoeuvered around a lot and not do all that much.
In my mind, Jolteon is a higher ceiling version of Alakazam as a lead, that just really doesn't want to face Rhydon. Whether or not you think this is worth it is based on how consistently you can get an advantage in the games where Jolt gets a fine matchup. I don't have a lot of love for lead Jolteon, because I feel like the huge leads it can generate can also be generated by other pokemon relatively often, and opting into the Rhydon fish just isn't necessary at all. Meh. I would run it in less serious games, but I'm unconvinced it's a part of the optimal mixed strategy of playing RBY in tournament.
Honorable mention to the Jolteon + back Jynx pairing. I didn't really consider this as a lead set, because it's pretty clearly a fake lead, you just want to swap jynx on enemy Starmie, and otherwise you're just twaving gengar and bolting into jynx(?). Swapping jynx on stuff like zam as well, context dependant. I don't know. I haven't played with it very often, but it's just another way of changing the jynx team's lead matchup spread a bit. It doesn't make anything too crazy but I think it's neat.
I got tired writing and I think anything beyond this would just be yap, but the long and short of it is I think that the rest set in the back has a couple of requirements, i.e: doesn't want to vs rhydon, doesn't want to vs rest egg(inversely likes to see egg rushing), wants to see zapdos. It has a similar matchup spread to Rhydon teams, but trades off losing to Rhydon teams in exchange for more tauros resilience(so better versus Everything Else). I think it crests the bar to be a part of the optimal mixed strategy, probably.
This isn't meant to be like, trying to be an arbiter of truth here. Just what I think about the pokemon. Good but not worth using more than sparingly.
