I absolutely love Meta Knight in doubles. He is definitely fit best for a carrying role, so the person who will be doing more of the work. His speed is great and his combos are fast (even at Doubles pace) so most of the time you can do combos without being disturbed. And if you so happen to get disturbed, he can flee easily from pressure and drop his combo voluntarily without worry. His edgeguards are amazing as many people will opt to land on stage if someone else is grabbing ledge already (most likely), so Dair, Bair, and Down-B cover these options (he can still cover the ledge pretty well if they do go to ledge). He is also very good at saving his teammates. Say my teammate is Fox and I'm onstage while he starts his Up-B. I can go under the animation of the Up-B and Up-Air Fox 1 to 2 times then tornado both of us back to safety onto stage. Soft Nair is also good for saving teammates. His 1v2 capability is out of this world, too. The sword can make sure each teammate is never together & always on opposite sides of MK/makes every encounter a 1v1 & not a 1v2. 2v1's are obviously amazing because teammate grab -> MK Down-B is very good. Just in general, his team combos are very good.
Overall, great neutral game (even though neutral isn't as prevalent in Doubles than it is in Singles), great combo game, can punish very well and hard (which makes him a good carry), amazing edgeguarding tools, can save teammates pretty easily and safely, can hold his own in 1v2's and does stupidly well in 2v1's.
I would say he's easily a Top 7 character in Doubles (off the top of my head & without making a solid list) and does very well against the majority of the cast.
EDIT: Just changed the wording slightly in my paragraphs.
