i think:
fox/jiggs
marth/sheik
jiggs/sheik
fox/falcon
fox/sheik
marth/falcon
falco/ sheik
edit (reasons):
fox/jiggs: fox has the up kills, and shinespikes, puff has amazing off stage fighting ability, aswell as saving fox off the edge, both characters have good spacing if done correctly, puff can use wop on bottom floor, while fox spams lasers on panels for funzies,puff and fox are both good in team, the best imo
marth/sheik, falcon/marth: does this really need explaining?, we have all seen a good sheik/ marth, and c.falcon/marth team
jiggs/sheik: idk this one is just kool to see, sheik and puff have good/easier combos, and combined they **** off stage and on
fox/falcon: awsome combos, gimps from fox, the thing about teams i want to keep into consideration is also the fact that if you did like fox/falco, they could go double marth and counterpick both characters, so i try to keep 2 characters, that no one character can counterpick them both, so that if they counterpick one of the team members then your other one counter pick them..... for instance in this matchup marth counters fox, but falcon counters falcon. falco counters both, but lasers are spammed less in teams, so you dont laser your partner.
fox/ sheik: great combos, both amazing at gimping, the one problem i feel from this team is that they really cant help eachother off the edge like falco could or jiggs could, the only reason im not putting to many falco in my list, is because i dont like him, and im kinda bias then, but falco is good in teams also
falco/ sheik: basicly same as fox/sheik, another thing i like to think about is, how good the character will do agaisnt 1 character while his friend is busy, because if i play falco in teams im not gonna laser a lot, because it may hurt my partner, so i think falco loses a little spacing in teams, other than that i think this is a pretty solid team
ps: i really didnt put this in order, i dont think it matters, its more about the players anyway