Playing Fire Red!

Its a little later in the game in cerulean city (whatever the big city in red is) or somthing. A npc mentions it.

You get Eevee in Celadon City. To get it you go north(up behind the Pokémon Center) and west to enter a building from the back. You then go to the roof and enter a little studio at the top where there is a Poké Ball with Eevee inside. Celadon City PokéMart is also the only one that sells TM’s, Vitamins, and Evolution stones, hence you can evolve Eevee immediately upon acquiring it. With the Thunderbolt TM from Surge, Jolteon would be ready to roll at that point in the game. The roof of the Mart is also important since you’ll want to buy Drinks(Fresh Water, Soda Pop and Lemondade). If you get one of each and give them to an NPC up there, you get free TM’s, including an extremely good one in Ice Beam(at least it’s that way in RBY, not sure if it’s the same in FRLG). You’ll also want another Fresh Water for when you venture into Saffron City(can’t get in otherwise).

Also, if you haven’t fought Brock yet, if you backtrack to Viridian City and head West onto Route 22, you’ll encounter more useful Pokémon for you to catch(Mankey, both Nidoran and Spearow) in the patch of grass near a ledge. Additionally you can trigger an optional rival fight by heading up and west. Your rival will have a level 9 Pidgey(its Spearow in Yellow) and a level 8 Starter(one that beats yours or Eevee in Yellow). For Yellow players only, it’s a notable fight because it dictates what his Eevee evolves into and you must fight and beat him if you want him to do Jolteon. If you skip it but win the first fight, he does Flareon(that or lose/win or win/lose, the latter isn’t fun though). Only way for him to do Vaporeon is to lose the first fight and either skip/lose the Route 22 fight. So yeah, just something to note. It’s also possible in Red/Blue/Yellow to get unique dialogue from Oak after beating him on Route 22 with you just having your starter and nothing else. Whether they kept that in FRLG I don’t know but Oak doesn’t give you Poké Balls when he gives you the Dex(you have to buy them). If you defeat your rival and go back to Oak, he gives you 5 Poké Balls along with the unique dialogue. Only instance where you get something from him that should have been given to you but then Gen 1 doesn’t hold your hand.

I just started a nuzlocke of X/Y and for funzies I chose the girl and named her Izzy~

Just be aware that Lance has specific counters against it. Gyarados can Bite it to death(even with god awful 60 SpA). and Aerodactyl can OHKO it thanks to its Speed and Rock STAB. I should note though that the move Hidden Power(TM10), is an incredible coverage option for Physical Attackers in Gens 2-3 since it's a Normal Type move and hence is Physical. Yet I don't know where to determine what type of attack it happens to be save through trial and error. Yet it's power varies if memory serves and if you put it on a Pokémon with Technician(like Scyther), it could be stronger than X-Scissor/Lunge if it turns out to be Bug(since 60 x 1.5 → 90 which then gains STAB). Meowth also has Technician but HP cannot be Normal for it to gain STAB on it(makes a great coverage move though).