No MetaKnight is still MetaKnight. Tornado still ****s everything up, and Shuttle Loop is still cheap as **** as well. Only thing MetaKnight has to watch out for is people not to gang up on him, but that's FFA for ya.
MetaKnight is still MetaKnight. He 's not worse in FFA at all. That's why you see him being played all the time still in Team Battles, which is more or less the same hing.
And of coarse you have to be good at him. But you have to be good at Ike and Pikachu as well. Why would anyone pick a character they're not good at?
So yeah, MetaKnight is still good, quite possibly still the best even. Perhaps Pikachu being his sole rival (or better: Thunder). Only thing he has to worry about is peopke ganging up on him, for him being MetaKnight. You always take down the most powerful first.
Yes, DK is a big target, and easy to combo. But you'll need to watch your zoning space with him a lot, especially in FFA, but that's what DK is good at. He's definitely not an easy pick for anyone, but DK-mains can easily keep with their character in FFA I feel.