Splash_King
The Scrubbiest of Hunters
PM's not a good competitive game
What defines how good a game is competitively is both balance and potential skill ceiling. Project: M is unfinished, so judging it based on flaws that will be corrected (character unbalance) is relatively unfair i.e. Sonic once broke the game, but he certainly doesn't anymore. Every other Smash game, however, is very much finished and are very much unbalanced in terms of character viability (and vBrawl's just-plain unbalanced). P:M has the upper hand here.
All Smash games have a high skill ceiling though, hence their competitive viability. P:M is very much a great competitive game, even despite it bein' unfinished.
Meta Knight should be an unlockable character. Use him right and he is overpowered. I don't know how to use his unbalanced gliding yet though.
Whether or not a character is unlocked from the start or is a secret character depends on a few things. Namely whether or not they've been a secret character in past games, as well as the order you encounter 'em in Subspace Emissary. Character balance doesn't come into it.
that aside meat night is most definitely op as hell tho