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.
Fanon Discontinuity: Some hardcore fans like to consider Mega Man 3 the true final game of the Mega Man Classic timeline, preferring to assume Dr. Wily died at the end of 3 and ignoring everything from 4 onwards. (some less hardcore fans like to consider the same of Mega Man 6, and ignore everything from Mega Man 7 onwards)
Fridge Logic: Why is Pharaoh Man weak agains bright lights when he's using a fire based weapon that also emits a bright light?
Fridge Brilliance: Flash Stopper is a time based weapon. Pharoah Man is essentially a mummy, whose bodies degrade over time.
That One Boss: Pharoah Man if you don't have his weakness (you do and he's a pushover), as he's really fast and hits hard.
Also Bright Man, who can stun and then jump on you for massive crash damage.
Then there's Ring Man, who can cause huge crash damage and counterattack if you shoot him on the ground.
The Wily Machine, if you don't know that you can detonate the Drill Bomb in mid-flight. This can lead to having to resort to Outside The Box Tactics such as trying wire, Rush Jet, or Rush Coil in an attempt to hit that just-out-of-reach weak spot.