what are the odds of being banned
depends on what exactly you did, and how aggressive they are with cheating in pokemon game.
If you made everything look like legit pokemon and did it offline, it might not be a problem.
If you created obviously cheated pokemon and used them online or modified online battle results you might get banned, depending on how aggressive gamefreak/nitnendo is in pokemon, what exactly you did and how much they check.
Generally, you need to evaluate it on a game to game basis when talking about cheating and using mods in games, single player only games with no online connectivity are normally safe, singleplayer games with only some online connectivity might be safe, depending on what you are doing and what the devs implemented.
mainly online games are sometimes safe in private lobbies or for offline, sometimes they are only safe if you know what you are doing, and sometimes they are just not safe.
Just do some research about the specific game you want to know about, like in this case pokemon, and check some already existing posts about whats safe, and what not.