So in my opinion the Metal Gear Solid franchise has the best boss encounters and boss mechanics compared to any other game ive played.
From MGS1(Playstation): Psycho Mantis fight which was really creepy in atmosphere and you had to do the controller switch which was really cool
From MGS2: Not so many cool ones as this game was abit guff but the Fat Man fight where you had to go around defusing the bombs while he tried to rollerskate over your face was cool, plus fighting the hundreds of Metal Gears at the end was epic.
From MGS3: You had the Fear fight where you had to track him through trees whilst avoiding his traps and poisons. And The End's fight where you had to track him via his footprints on the ground (especially hard when you were going for his camo).
From MGS4: The Crying Wolf fight where you had to stay downwind of her constantly because she could smell you and would track you down, not to mention the fight was in a blizzard where you could see very little. Also the return of the Psycho Mantis was a really well structured fight too as you now had to supress your nano machines then take down the mind control dolls.
Anyway thoughts or opinions on other cool boss encounters