0135 Jolteon

While Thunder Shock doesn't have as much raw damage output as Volt Switch, the significantly higher energy gains easily make up for this. 

Of all the options Jolteon has for its charge moves, Discharge stands out as the cheapest option in terms of energy, which also makes it the best option to bait shields. Thunder costs only 5 more energy than Thunderbolt, but deals more Damage Per Energy (DPE) which makes it the more valuable pick. Last Resort could be an option to deal neutral damage should Electric-type damage be resisted, but the lack of power and STAB causes Jolteon to lose way more matchups against most of the meta. Zap Cannon demands way too much energy to be consistently viable. 

Jolteon is an offensive powerhouse in PvP, with an emphasis on frequent and powerful STAB charge moves thanks to the best energy generation in the game. A shield bait with Discharge and a direct hit from Thunder is often enough to severely wound if not KO most opponents who don't resist Electric-type attacks. Unfortunately Jolteon's offensive power ultimately is held back by its unsurprisingly low durability, which makes tankier competitors like Melmetal and Lanturn more appealing to use. Overall an interesting pick that can definitely catch opponents off guard if they're unprepared. 

Ultra League is notable for the significantly greater presence of Dragon-types which resist Electric-type damage, and thus Jolteon has somewhat of a harder time trying to find its role in this league. Wins against Umbreon, Poliwrath, and Lapras are definitely appreciated, but losses against most of the meta makes it difficult to choose Jolteon as Giratina's bodyguard. 

With a max CP of 2888, Jolteon lacks the stats to compete against the numerous legendaries in Master League.