It must be leveled at day, 10:00 AM to 5:59 PM with high happiness. It will not evolve at morning, and if it levels at night with high happiness it will evolve into umbreon, never to become Espeon.
You use a water stone.
Evolve Eevee during the day
Evee will evolve to espeon if it has max friendship with its trainer and if its morning.
If you want Eevee to evolve into Espeon then train it during the day, other way 'round for umbreon (On LGFR you need the National Dex)
In Pokémon Platinum, the Thunderstone will work on only Pikachu and Eevee. Using the Thunderstone on Pikachu will allow any Pikachu to evolve into a Raichu and using it on Eevee will allow you to evolve into Jolteon.
In order to evolve Eevee into the Psychic-type Pokémon, Espeon, you need to get Eevee's happiness to a certain level during the day time (4am to 8pm). You can do this by leveling it up, having it in your party, even walking with it. There are several other options as well, depending on exactly what game you're playing such as giving it massages and feeding it Vitamins such as Protein and Iron.
Evolve it from eevee
Ive hear my friends say that in Pokemon yellow you can evolve eevee in a espeon with a moon stone
You can't. It evolves by the time of day. Since there isn't a clock, eevee won't evolve into espeon OR umbreon.
give it a thunderstone
Max out Eevee's happiness during the day. ~KKMG1
You will get an eevee egg. That you can evolve into an eevee or the other eevee evolutions.
espeon evolves from Eevee fromHappiness during the day, or when around a Sun Shard
There a lots of ways to evolve Pokemon in Pokemon platinum. 1. When some Pokemon reach a certain level they evolve. 2. For some Pokemon like eevee u have to use an evolutionary stone. 3.To get eevee to Umbroen or Espeon u have to make eevee have max happiness. Then level it up in the day and u get espeon and level it up in the night and u get umbroen. 4. Some Pokemon such as riolu and togepi require to be happy to evolve. 5. For Pokemon like haunter u have to trade a it. As soon as it is traded it will evolve. 6. Some Pokemon like legendary Pokemon can't evolve.
You have to level it up with high happiness during the day(10:00 AM to 5:59 PM).
You have to get an Eevee and evolve it with full friendship during the day. Try giving Eevee the item Soothe Bell, it makes the Pokemon become friendlier way faster.
Evolve Eevee during the day
When Eevee loves you, level it up in the Morning.