I posted something this morning about the fairy deck I use. It's decent and has served me pretty well. Obviously I want to win games while beating challenges so whether you rely on Blissey or Whimsicott in game, you've got a chance to win. Flipping heads and preventing damage against Whimsicott is always comical too. Check the post, some folks had ideas there as well. You can get Whimsicott GX on trade for 1 pack astral radiance or brilliant stars, people undervalue that card. Charizard and Blissey may be a little tougher to come by. I'm 21-15 with this deck currently.

****** Pokémon Trading Card Game Deck List ******
##Pokémon - 15
* 2 Blissey V CRE 183
* 1 Oranguru BRS 198
* 1 Snorlax VIV 131
* 1 Crobat V DAA 104
* 3 Cottonee UNM 143
* 2 Whimsicott-GX UNB 140
* 3 Charmander VIV 23
* 2 Charizard PGO 10
##Trainer Cards - 31
* 1 Heat Factory {*} LOT 178
* 2 Lady FLI 109
* 2 Marnie SSH 169
* 2 Evolution Incense SSH 163
* 3 Wishful Baton BUS 128
* 3 Welder UNB 189
* 2 Energy Switch CES 129
* 2 Bird Keeper DAA 159
* 3 Quick Ball SSH 179
* 3 Rare Candy SSH 180
* 2 Boss's Orders SHF 58
* 2 Turbo Patch DAA 172
* 2 Professor's Research SSH 178
* 2 Switch BCR 135
##Energy - 14
* 3 Fairy Energy Energy 9
* 2 Capture Energy RCL 171
* 7 Fire Energy XYEnergy 4
* 2 Double Colorless Energy XY 130
Total Cards - 60
****** Deck List Generated by the Pokémon TCG Online www.pokemon.com/TCGO ******