RE: Your favorite deck
It probably would help to read the 1st post before making one of my own.
1) Delta Reactor - Gyarados, Delta Flygon, Delta Flygon Ex, Delta Nidoqueen.
This deck used a lot of cards that were popular back in the Delta Era, but the main focus was my own design. Gyarados has a body that says, so long as a Holon Stadium is in play, all of your Delta pokemon do 10 more damage to the defending. The goal was to get 3 in play so I would always have a continuous, triple PlusPower. Gyarados attacks were fairly bad, so everyone deemed him bad as well, but i felt his body made up for it. Nidoqueen let me search my deck for any Pokemon and was a nice revenge-killer, seeing as it it did 30 + 10 more for each Pokemon in my graveyard (capping at 60 extra damage). With a full graveyard and 3 Gyarados in play, i was able to tank and hit for a max of 120. Flygon let me add an extra Basic or Delta Rainbow energy into play each turn and Flygon EX had a body that spread 10 to my foes basic pokemon between turns.
It was my first semi-competitive deck and I miss it.
2) AMU, Platinum Gardevior, Mewtwo Lv. X. (AMU2)
AMU = Azelf, Mesprit, and Uxie. I played it after it stopped being popular, as that's how long it took me to get the cards. Uxie had a power which let you draw until you were holding 7 cards and its Lv. X had a power that let you look at the top 2 cards of your deck. choose 1 to keep, and put the other on the bottom. Azelf had a power that let you look at your prizes, take a pokemon from there, and replace it with a card from your hand. It's Lv. X had a body which canceled out your psychic pokemon's weakness and it's attack did great snipe damage. Mesprit had a power that kept your opponent from using powers on their next turn. It's Lv. X let it attack the defending for 200 at the cost of discarding all energy, so long as your other Lv. X's were in play. Mewtwo had a free attack that let it grab 2 energy from the discard and give them to itself. It's Lv. X attacked for 120 and the cost of discarding all energy, but it's body prevented it from being effected or hurt by non-evolved pokemon. Gardevoir had decent attacks and a power that let you freely shift your psychic energy around, allowing you to power up whichever attacker you wished. It's Lv. X had a power that let you move it to the bench or the active spot at will and an attack that let you KO the weakest pokemon in play.
I had a lot of fun with it and it was my second competitive deck.