Lucky 7777's is really cool...if you ask me. Heres how it works:
First off, there is no easy way to get Lucky 7777's, unless you have a gameshark. See when your in a battle "hopefully Emerlad or Ruby!" if the enemy hits you, and blows your HP down to 7777 no more no less...then who ever has 7777 as there HP will go bizerk on the enemy(s) untill the enemy(s) is/are dead!
Its really fun to watch, but for me, it only happened once in the whole game...and it was in a battle for a Wonderfull Chocobo at the Glacier area, well here is this poor Chocobo that I was "gonna catch" but I forgot that RED XIII had counter materia on him, so the enemy attacked, and RED XIII goes down to all 7's, and just beats the crap out of every enemy and the poor old Wonderfull Chocobo, that I needed to make my Gold one...well atleast in this game the Chocobos cant run and tell there friends to watch out for you...
From Super FF7 Staff
All Lucky 7's Trick First, make sure everyone has over 8000hp. go to the wutai area on the beach. get into the battle and use demi3 on everyone until they have less than 154hp. go on the highwind and equip the cat's bell accessory. walk until each character has exactly 154hp. Go back to the beach and battle. use demi2 on everyone once. use 15 hi-potions and 2 potions each oneveryone outside of battle. you should have 7777hp.
To get all 7's make sure that everybody has 8000 or more total hp of course and less than 7000 curent hp and his hp is an odd number then use the cats bell until he has his last two digits as 77 then use hi potions and potions until he is exactly all 7's. for example if you made his hp 5877 then use 3 hi potions and 4 potions. or if you have 4077 then use 5 hi potions and 3 potions.
IF ANYONE CAN TELL MORE WAYS TO GET LUCKY 7777'S WITHOUT, I WOULD LIKE TO POST IT ON HERE, THERE IS A LINK AT THE BOTTOM TO E-MAIL ME, I AM LOOKING FORWARD TO HEARING YOUR IDEAS AND METHODS ON HOW TO GET TO IT!