Xbox 360 live multiplayer question

Can 2 players play Xbox live from the same console at the sametime? For example 2 players using the same console to team up and play other gamers online.

90% of games yes . I do want to say 100% , but no games come to mind that doesnt.

do both players need a live account?

if they are on the same console , no.

Only one needs a Live account, but I think the 2nd player needs a profile.

"Only one needs a Live account, but I think the 2nd player needs a profile."-Correct.