This deck is based on weakness! Use Kabutops and Mirage Gate to guarantee OHKOs with Kecleon. If you have trouble with decks featuring Pokémon with abilites where they have no weakness, you can include cancelling cologne. You can use Porygon as a tech against Dragon types, but since I have a Psychic Energy, I can run Sableye and play like a normal lost box.
Start with Comfey and Colress's Experiment and Battle VIP. We want to use mirage gate and have Kabutops ready ASAP to start destroying with Kecleon. Radiant Greninja can be used to discard unneeded types of energy to draw more cards. With this deck, OHKOs are guaranteed. Ho-Oh V is an emergency option which can be discarded using ultra ball and Thortoned into Kecleon.
You could add more Lost Zone oriented cards, such as Cramorant, but cram is just inferior to Kecleon due to weakness. Mirage Gate is just the best way to power up Kecleon.
If you want a better version check out my Water Kecleon deck!