Yeah, Jolteon's cool.
In my Emerald, I have one that's Calm nature
252 Sp. Atk., 129 Speed, 129 Sp. Def. (Um guessing-I'm ot sure if Emerald has one who rates EVs)
Rain Dance (I had BP before, bit it was useless for mine)
So Jolteon's awesome if it has a good -atk. nature, because it doesn't get a good physical movepool in gen. III. (The only ones were Pin Missile, Bite, Take Down, Quick Attack, and Tackle) In Gen. IV, they got Thunder Fang, but that's kind of crappy compared to special Jolteon. So yeah.
Arcanine could be...
Crunch (Not sure if it can learn it in IV. If not, get one from FR/LG)
Flare Blitz/Fire Blast
I find that the first set is cooler, as I own one (with WoW instead of Sub.), but it's your choice. As for EVs, you can choose too. I don't know about mine, because I just got it over from FR and taught it all the moves mentioned above (the first two were already there). Yeah, for a Luxray try...
Intimidate/Rivalry (your choice)
Spark/any other move you like
Obviously, I'm a huge fan of Spark, because someone else would never suggest it on a Luxray. Maybe a Pachirisu, but who would use one for competitive use? Amyway, Thunder Fang's a great STAB+flinch/status problem, so that's cool. Ice Fang's sort of the same concept, except going to affect Ground types with a Ice type attack and no STAB. Crunch is a strong attack, and spark... well, I like it, okay? If you don't like it, then you can change to something that you prefer.