Psycho Mantis - I mean let's think back. Creepy voice, controlled Meryl as a weapon, he broke the fourth wall and he was hard if you didn't cheat aka plug your controller into port 2.
No question about it; this is by far the best boss fight ever.
Not sure if they count as bosses as they were optional fights but...
Emerald Weapon in FFVII
Omega Weapon in FFVIII
Penance in FFX (the mother of all battles just as long as you didn't use Yojimbo and get his Zanmato move)
Comments
It took me 10 years to finally beat him
No question about it; this is by far the best boss fight ever.
http://www.youtube.com/watch?v=MEvRzbLc8V8 Rocket Knight Adventures Round 6 boss - obvious Gradius influence here!
Emerald Weapon in FFVII
Omega Weapon in FFVIII
Penance in FFX (the mother of all battles just as long as you didn't use Yojimbo and get his Zanmato move)