If you are playing expanded, you can have a look at this deck list i have made.
****** Pokémon Trading Card Game Deck List ******
##Pokémon - 19
* 3 Eevee SUM 101
* 1 Oranguru SUM 113
* 2 Shaymin-EX ROS 77
* 1 Type: Null UPR 115
* 1 Type: Null CIN 89
* 2 Silvally-GX CIN 108
* 1 Flareon AOR 13
* 2 Leafeon-GX UPR 13
* 1 Jolteon AOR 26
* 1 Dawn Wings Necrozma-GX UPR 63
* 2 Tapu Lele-GX GRI 60
* 2 Glaceon-GX UPR 141
##Trainer Cards - 31
* 2 Professor Sycamore STS 114
* 1 Computer Search BCR 137
* 2 Winona ROS 96
* 2 Choice Band GRI 121
* 2 Professor's Letter BKT 146
* 3 Ultra Ball PLB 90
* 1 Super Rod BKT 149
* 1 Ninja Boy STS 103
* 1 Nest Ball SUM 123
* 1 Hau GRI 144
* 2 Guzma BUS 115
* 2 VS Seeker ROS 110
* 1 Field Blower GRI 163
* 1 Trainers' Mail ROS 92
* 1 Professor Kukui SUM 148
* 1 N NVI 101
* 2 Sky Field ROS 89
* 1 Aether Paradise Conservation Area GRI 116
* 2 Pokémon Communication BLW 99
* 2 Level Ball NXD 89
##Energy - 10
* 3 Water Energy 3
* 4 Double Colorless Energy XY 130
* 3 Grass Energy 1
Total Cards - 60
****** Deck List Generated by the Pokémon TCG Online
www.pokemon.com/TCGO ******
The deck does not focus on using Grand Bloom Gx while this can also be an option. I feel like Grand Bloom is a very sub-optimal Gx attack. Second turn is usually a turn where you would much rather be attacking. Leafeon-Gx is a good backup attacker in this deck that you can use after starting off with Glaceon-Gx. The healing ability is then very useful often times and it gives you a different type to attack with.
So 1st turn you use Winona to set up (Eevee, Shaymin, Type: Null). Ideally you want to send Glaceon-Gx in the active for Freezing Gaze.
Turn 2 you can do another Winona (Silvally-Gx, Shaymin, another Eevee or Oranguru). Use Pokémon Communication, Ultra Ball, Nest Ball or Level Ball in order to find your bench supporters (Jolteon, Flareon, DW Necrozma and Silvally-Gx). If all goes as planned, you now have free retreat, ability lock from Freezing Gaze while preparing Leafeon-Gx out in order to replace Glaceon-Gx and heal it back.
I made this deck for my Girl. She likes the Eeveelution's a lot (so cute). Supporter's are not optimal since i used for this list the Full Art cards i had instead of trying to max out efficiency but you surely get the idea.
As far as Standard is concerned i feel like Leafeon-Gx could work to some extend using as you said Gardenia/Aether Paradise Conservation and such. But then you could just use a deck like Zoroark-Gx/Lucario-Gx with Acerola since it is way more consistent. I feel like pairing it with Glaceon-Gx would still be the best way to play it since Glaceon-Gx as an easier time dealing with the current meta. Focus on getting out Glaceon-Gx first turn and prepare a Leafeon-Gx as a backup attacker. Replace Winona and Shaymin with draw support Brigette and Nest Ball, etc...
I hope this helps.
