Decklist from LittleRiver.
This deck uses Electrode ex to attach lots of Energy onto Exeggutor for its Big Eggsplosion attack. Electrode ex KOing itself also turns on Scramble Energy for more damage, and Pow! Hand Extension to drag vulnerable Pokémon out for Exeggutor to KO.
(The name of this deck comes from Scramble Energy and Exeggutor.)
Lead with Exeggcute, evolve it into Exeggutor, and use Psychic Exchange to set up. Build more Exeggutors and Electrode ex's on your Bench. Continue to attach Energy and switch to attacking with Big Eggsplosion when you're ready. Double Rainbow Energy provides a big boost if Scramble Energy isn't live yet.
Getting Energy into the discard pile for Electrode ex's Extra Energy Bomb is a bit tougher with this deck compared to others that use Holon Supporters. TV Reporter is the only Supporter in this deck that discards, and you don't have as many copies of it as Holon Supporters + Transceivers in other decks. You can have Voltorb use Recharge to get Lightning Energy from the deck, which secures at least 2 Energy for Extra Energy Bomb, and possibly even get a bit of damage in with Electrode ex's Crush and Burn before you blow it up. Retreating and losing Pokémon to KOs are other ways that Energy can end up in your discard pile through natural play.
This deck has both Cessation Crystal and a Pokémon with a Power, so you should be mindful not to lock yourself out of your own Extra Energy Bomb. If you've got an Electrode ex in play and a Cessation Crystal in hand, blow up Electrode ex before attaching the Crystal. If you attached Crystal to your Active Exeggutor and only drew into Electrode ex later, you can retreat Exeggutor to Electrode ex to disable Crystal, then use Extra Energy Bomb to attach Energy to that Exeggutor and simultaneously get it Active again.
This deck plays a low Supporter count, and instead has Great Ball and Master Ball where the Pokémon-searching Supporters would be. Psychic Exchange draws you a fresh hand of 8, and you would rather have multiple Balls in that hand than multiple Supporters (which are once-per-turn), even if Master Ball is unreliable.
This deck uses a 3-4 Electrode ex line. The 3 Voltorb makes it more likely to start with Exeggcute, and the 4 Electrode ex is because this deck draws a lot of cards with Psychic Exchange but doesn't have good Pokémon-searching options, so you play as many Electrode ex as possible to maximize the chances of drawing into it.
This deck has Holon Energy GL to protect against Special Conditions and reduce damage from ex's. Castaway comes in handy if you need to search for Grass or Lightning Energy.
A common question you'll ask yourself is whether you have enough Energy on Exeggutor to reliably KO your opponent's Pokémon. Refer to the grid below for the probabilities (in %): the top row is how many Energy you have attached, and the left column is how many heads you need for a KO.
Heal Energy over Holon Energy GL: Also cures Special Conditions, but only once, and doesn't cure when attached from the discard via Extra Energy Bomb.
Poké Ball, Professor Elm's Training Method: Alternatives to Master Ball. Elm is the most reliable, but it's a Supporter. I have just 1 copy of Elm as a tutor target off Castaway.
Magnetic Storm over 1 Windstorm: This retains the number of Stadium-removing cards, and loses Windstorm's Tool-removing functionality in favor of letting Exeggutor hit through Resistance.
Exeggcute RG: It can steal games with Confusion, but you'd need two coin flips to go your way (one for proccing Confusion and another for your opponent to hit themselves).
This deck runs only two Stage 1 Evolution lines, so it can get set up relatively quickly.
Exeggutor can hit for huge amounts of (single-target) damage, KOing both high-HP ex's and Pokémon that try to tank damage with Metal Energy.
Big Eggsplosion's damage is luck-based, and it's completely possible that you get RNG screwed. It happens, just like every other coin flip in the game. If you've seen a sleeping Pokémon not wake up within 3+ coin flips, you'll also see Big Eggsplosion fall flat on its face and fail to KO something that it should have.
Crystal Beach reduces the amount of Energy that Double Rainbow and Scramble provide, and causes them to provide only Colorless, forcing you to have Psychic Energy to attack through it. Windstorm can get rid of Beach.
Some Pokémon (such as Psychic Boom Ralts) have attacks that do more damage if the Defending Pokémon has more Energy attached to it. These can revenge kill Exeggutor for cheap, especially if they hit for Weakness.