I got a bit of an issue with Dragon's description for both Psycho Shift and Psychic Terrain.
First off, I actually do believe that Psycho Shift is some form of Mind Manipulation. As the description for the move says, it creates a suggestion in the opponent's mind, which causes the status to shift from the user to the target. This is probably refering to a similar type of ability that RW hypnotists have, which is to create suggestions in the mind that causes people to experience things that are all just in the mind. For instance, causing someone to believe they're broiling hot, despite the fact that they're sitting in a freezer. So, Mind Manipulation, albiet on an inhuman level.
Second, labelling Psychic Terrain as game mechanics essetially is trying to remove it from being used entirely, since game mechanics are not really meant to be utilized. Plus, this would cause Tapu Lele's ability, Psychic Surge, to be utterly pointless. And as it's been displayed in both the anime and manga as being a field of psychic energy just like the games, both created by Tapu Lele mind you, this should technically be described as a field effect where psychic energy is overflowing throughout the duration. This would also explain its secondary ability, which is to protect against priority moves, since the Pokemon would gain a minimal amount of psychic powers while Psychic Terrain is in effect and be able to predict where the priority move is going to take place and either evade or block them, which would normally strike its opponent before they can react.