It's Zack.The need is in the small FMV in the Shinra Mansion where you see Cloud throwing Sephiroth into the lifestream.Then,both he and Zack got experimented by Hojo.At the end of the FMV,you see Zack sacrificing himself to protect Cloud by using his own body as a shield.Though Cloud was somewhat...weird,he knew that Zack thinks that he is his friend.

A strong freind in need--->Zack is strong,he's SOLDIER first class.he helps Cloud escape from the mansion,therefore he helps you in need.
Is a great friend indeed--->Zack sacrificing himself to protect Cloud from the Shinra Soldiers,thereore,he is a great friend.

In conclusion,I got the riddle,obviously,from an old saying,'A friend in need is a friend indeed',I only added a few words.Although the riddle could mean anyone,but the hints narrow it down fast.

Well,my riddles are actually quite simple,so I will only accept one answer at a time.Each riddler has their own style.You're up,Lost Number.