After you defeat the Jumbo Cock Boss in the Cave of Origin during Generation 1, you can
go back down into the Boss room in the dungeon and encounter the Boss again during random
battles. If your party is still somewhat weak, then this can be a challenge because he 
can also spawn with as many as eight other monsters. The rewards as far as experience, 
gold, TP, and EP really stack up as you are able to win the battle faster. Save the game
after each fight so you do not lose your levels, since this battle can go bad very quickly.
Also, this is the only room you can find Mandrakes also which is required for the Cave of 
Origins Title located at the Adventurer Hall, the requirement of which is to kill fifteen 
of each monster in the dungeon.