Any team with Meta Knight + Power bruiser (Falcon, Ike, Bowser, heck, even Pikachu) is better than a doubles of Meta Knights. The pair of Metas have to put a lot more work into a KO, and the idea of double teaming leaves them with a second man to start wailing on one of your Metas.
The Ike + Meta team Ike isn't supposed to do more than not-die at first. Ike's KO range is a lot lower than anyone else right now shown. Meta pounds the percentages into one, Ike just makes sure the other doesn't kill him, when Meta gets the other off the edge, Ike and Meta switch. Ike is a killer edgeguard, Meta starts soaking percantages into the other opponent. The two opposites cover each other's weaknesses.
If the opponent attempts to double team Meta Knight, Ike can run over and try to kill all 3 in one shot. If they team up on Ike, Meta Knight pulls one into a Drill Dive and Ike goes back to just defending from the other. And you start out with Meta taking on the stronger opponent (team of Fox and Jiggs, Meta take on Fox, etc).
Double Meta Knight will take a lot more time to get a KO, even if you swapped one out for a slightly slower but still combo friendly (Pikachu, Jiggs, Fox) character with better KO moves you'd do better than double Meta.