Don't list Mega Metagross as a sufferer of 4MSS, please. Even if you believe it it's a rather controversial statement. I'd go for something like Lucario instead.Term: 4MSS
Explanation: Four Move Slot Syndrome. When a Pokémon has a vast collection of viable moves from which the user can only choose four.
Example: Mega Metagross
Reference: Personal Experience and Other Users
In addition, you actually have the terminology completely wrong as this would apply to every Pokémon in existence aside from what, Magnezone? The correct definition is "When a Pokémon has five or more moves it needs to be used successfully, but may only use four". Hence the Lucario example - fuck it I'm just gonna do it
Term: 4MSS
Explanation: In which a Pokémon has five or more moves it needs to be used successfully, but due to only having four moveslots cannot do this.
Example: Lucario's goal as a late-game cleaner means it needs Swords Dance to boost, Extremespeed for priority, Close Combat and/or Iron Tail for STAB and Ice Punch and Crunch for coverage. However, it may only choose four of these six moves and hence suffers from 4MSS.
Reference: Personal experience both on showdown and on the forums.