These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Dr. Ion is noticeably simpler than the rest of the bosses in the game, telegraphing every attack and failing to block. In-Universe, everyone notes that Dr. Ion is worthless before and after the fight, and he really just serves as an easier boss before Azel at the end of Stage 4.
Ravel is a Dreadful Musician with a very damaging long range combo, but with the lowest health of any boss and an exceedingly easy to dodge knockback move, the fight is pretty much over the second you manage to get in melee range. The rematch is only slightly harder because you have to learn the moves of Debussy, an equally long-ranged fighter, but a God Hand release and adequate pressure can knock them down without even letting them fight back.
Evil Is Sexy: Azel and Shannon. The latter... Just look at the flyer she leaves for Gene while he's out:
"Join us for Masochysteria! Take part in the world's most famous S&M show! Beginners more than welcome!"
8.8: The infamous IGN review that gave the game a 3.0 score is generally regarded as the worst piece of writing to ever be posted up and part of the reason the game flopped despite having such a cult following. Problems include complaining about things that aren't in the game and saying it's bad because it's too hard, finding the sense of humor to be weak, and other issues that make it seem like they hadn't played the game for more than a few hours. The review itself was also poorly written with multiple spelling errors that have gone unfixed to this day.
Good Bad Bug: It's possible to get the Great Sensei into a stun loop.
The same could be said about the Trident Demon. All you have to do is use the default sweep kick after doing your Square combo. Do note that he has to be carrying his trident in order for this to work. So it is actually better to not "pummel" him when he's dizzy, because if he drops the trident his attack pattern changes entirely (plus it's even more aggressive than before). See it in action