4-4 Donphan (3 prime, 1 hgss)
Pokemon total = 24
Energy Total = 20
2 flower shop
2 rare candy
Trainer/Supporter Total = 16
I'll start off by suggesting that you add one starter, a single cleffa, just in case you need to refresh your hand or stall for a while. I like the reuniculus to move damage around, but you should be safe with a 3-2-2 line. You can also drop the HGSS donphan since 3 donphan prime should be more than enough. I'm not sure which magmortar you're including, but I want to think that it's the one that discards cards from your opponents deck equal to the number of energy attached to it. This is an interesting addition, without an energy accelerator like emboar, you'll have a hard time using it. I think dropping it and sticking to the zekrom, reuniculus and donphan should be enough. Adding in vileplume for a trainer lock deck would be an interesting combination, but only if you're willing to play without trainers as well.
I'd drop the fire and psychic energy, keeping the rest for a total of 12 energy, which should be more than enough.
You've got a great start with 4 pokemon collector. I'd add in 2-3 pokemon catcher to bring up your opponents benched pokemon, 4 junk arm to reuse any trainers, 3 communication to make sure you get the trainers that you need, another PONT to increase your hand shuffling, a few cheren to have some draw power, and max potion so you can get rid of some of the damage on the field. You should be able to drop one flower shop and all the pokedex. Adding in a switch will prevent you from having to pay the retreat cost. If you have any more available spots, you might want to consider juniper and pluspower.
This is similar to 'The Truth', a deck that won 2nd place at worlds, but it's missing vileplume. It would be easy to make a few adjustments to make this a trainer lock deck (adding in sage, reducing your own trainers, etc....) Otherwise you have some very strong attackers which should be able to last a long time with the reuniculus sitting on the bench.