Originally Posted by Fat Jorgen
It outspeeds Dugtrio and gets Baton Pass for getting out of there. I'm not entirely sure what the allure is, Zapdos seems much better as a BPer and as an all-around Pokemon, plus thanks to its Flying typing it has nothing to fear from Duggy, even when Para'd. I guess the lack of an Ice weakness goes a long way, and outspeeding Gengar, +1 DDtar, and tying Aero are nice things to do, too. Jolteon is probably at its best and most consistent in ADV from what I've seen, though.[/B]
Jolt is more synergetic with Skarm, Gyarados, Aero, Starmie, and possibly a few others that I can't think of right now. Zapdos is generally better for teams as its bulky, has an overall better defensive typing (Jolt handles BoltBeam better, but thats it), and a slightly more diverse movepool (I think all Jolt gets over Zapdos is Wish, which is...eh) but in terms of baiting attacks and forcing switches, Jolteon fares moderately better when paired with those mons. Jolteon getting up a Sub is basically a free switch with the bonus of switch advantage- thus, Jolteon is capable of forcing your opponent to double switch without you risking yourself mispredicting and losing something important by simply passing to an appropriate counter to whatever is staring you down. Triangles suggested a Roar set without Sub- personally, I find a Roar set without Hidden Power more effective as it capitalises completely on Jolteons ability to force switches- with a few layers of Spikes and a good sense of prediction, you can toy with your opponent, Roaring away counters and Subbing up on anything else. Jolteon also has the fastest Roar in the game, which lets you outphaze Zapdos who try to Roar away your Sub.
Jolteon has its place. It's not better than Zapdos, but there are times where Jolteon will outshine Zapdos. Jolteon will work much, much better with the pokes I mentioned, but Zapdos is a consistent threat.