Now that the submissions are finally open, here are my ideas. But honestly, to the reply with the litwick picture, the stat management is pretty difficult for me to digest. So I'm just doing it my way as to how I see the stat management for my eeveelution 'submissions'.
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Since this is about eeveelutions, for me, the way they should look like should be something like
this coming from the creative ideas of this artist. For future eeveelution ideas along with previous entries, same thing from that link of the picture from GlitchSamo21 at deviantart.
Mega Espeon (Espeite)
Abilities: Synchronize /
Magic Bounce ===>
Prepper (May create a substitute upon entering battle)
Details: Prepper - the ability is an automatic substitute that may or may not happen.
Typing: Psychic ===> Psychic
Base HP = 65
Attack = 65 ========> 100 (+35)
Defense = 60 =======> 75 (+15)
Sp. Attack = 130 ====> 160 (+30)
Sp. Defense = 95 ====> 100 (+5)
Base Speed = 110 ===> 125 (+15)
Additional Moves: none
Flavor wise, I take the Pokémon Y dex entry of Espeon where her forked tail quivers prediction its opponent's next move. While Anticipation is nice on her, I just find that spicing up her ability could work. Hence the Prepper ability. It just won't work if it enters the field on the first turn of the battle. Let's say I'm fighting Conkeldurr with my weakened Jirachi. Switching out to my death fodder espeon (who did its job done already), Conkeldurr uses knock off on her. Normally, it should have killed her. But the ability activates upon entering the battlefield, the knock off hits the auto summoned substitute instead (ala protect.)
Mega Umbreon (Umbrite)
Abilities: Synchronize /
Inner Focus ===>
Blur (User may dodge Contact Moves.)
Details: Blur = Simply, it is like Snow Cloak / Sand Veil built for dodging some attacks that make contact only like Close Combat or U-Turn. But Earthquake and Stone Edge still hits it.
Typing: Dark ===> Dark
Base HP = 95
Attack = 65 =======> 130 (+65)
Defense = 110 =====> 90 (-20. transfer to sp. atk)
Sp. Attack = 60 ====> 120 (+60)
Sp. Defense = 130 ==> 90 (-40. transfer to sp. atk)
Base Speed = 65 ===> 100 (+35)
Additional Moves: Knock Off.
Inspired by Pokémon X's description where it hunts on the night and changes its genetic structure, I grab gameplay inspiration from my DOTA 2 competitive gameplay experience playing as Phantom Assassin. PA (short term) is most well known for being one of the most dangerous carries in the late game that can deal damage in the four digit mark of the thousand damage (ex. 1512). She's fairly tanky in a way as well but very weak to ability based attacks. Hence the ability Mega Umbreon has reflects Phantom Assassin's ability to dodge right click physical attacks from carries in DOTA 2 fairly well, and the reason why I made Umbreon's mega give up some of its bulk while maintaining enough to take a bit more hits.
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Mega Jumpluff (Jumplite)
Abilities: Chlorophyll / Leaf Guard /
Infiltrator ===>
Cotton Shed (Switches out to an ally when using Cotton Moves. Acts like Baton Pass that only works using two moves: Cotton Spore and Cotton Guard.)
Typing: Grass / Flying ===> Grass / Flying
Base HP = 75
Attack = 55 =======> 80 (+25)
Defense = 70 ======> 95 (+25)
Sp. Attack = 55 ====> 75(+20)
Sp. Defense = 95 ===> 120 (+25)
Base Speed = 110 ===> 115 (+5)
Additional Moves: Roost
Since jumpluff flies all over the world scattering cottons according to the pokedex, I emphasize that cotton shedding to its ability and moves. What Mega Jumpy can do is either slow down the enemy with Cotton Spore or buff itself with Cotton Guard. Since the ability gives +2 priority to cotton based moves, and switches out to its ally, it almost gets away instantly as a support mon. Simply, the ability is like prankster that only works for certain moves.