Long ago, I used an Action Replay code in generation five to unlock hidden abilities for the starter Pokémon, allowing me to enjoy my play-through with a Contrary Snivy line. I deactivated the cheats when I played competitively and/or finished my play-through and transferred my Serperior to Pokémon Bank and eventually Pokémon HOME. I also used the Action Replay to enable a code that simulated the Exp. Share feature to shorten the grind. I never used any cheats to give myself an unfair advantage though, but rather to enhance the experience of my own personal play-through. Other than that, I never cheated in a Pokémon game. The newer games are doing everything in their power to make Pokémon less of a grind and give you the chance to easily obtain hidden abilities. Oh, if abusing glitches count as cheating, then yes, in the generation I games, I abused the Missingno glitch to clone Rare Candies. To be fair, literally everybody did, so I wasn't alone. Recently, I also take advantage of the shiny Ditto glitch in the Virtual Console to ensure that I always catch a shiny Ditto before transferring it to Pokémon Bank and eventually to Pokémon HOME. I’ve also used the box trick glitch in the Virtual Console to clone the shiny Dittos that I caught to increase my chances of transferring said shiny Ditto to a newer game with perfect IVs.