Numerous villains were robbed of final villain status. I though Obito was going to be the last one, I though Madara was going to be the last one, I thought Kaguya was going to be the last one, but nooooooope.
-Asuka vs. Mass Production Evas (Neon Genesis Evangelion): From the lake epiphany to Asuka gaining the upper hand to she being brutally defeated, an unforgettable rollercoaster.
-Kenshin vs. Shishio (Rurouni Kenshin): An intelligent, very resilient enemy who even withstood the protagonist´s supposedly unstoppable ultimate attack
(at least its first phase)
. The clear peak of the series. I also loved Kenshin vs. Saito in the dojo.
-The Twelve Zodiac Houses (episodes 42 to 73 from Saint Seiya): The legendary Sanctuary saga has several memorable battles during which the Bronze Saints, as clearly underpowered as they were, got a streak of pyrrhic victories against the extremely well designed Gold Saints -who, in most cases, walked an interesting line between being antagonists and mentors-. The Phoenix Ikki vs. Virgo Shaka (arguably, the strongest from each side) fight is the one I would probably choose, but they were all excellent clashes.