If Psychic is supposed to be weak to common fears, then it should be weak to pretty much everything.
Fire - All organisms are naturally afraid of fire. That's why building a fire is a great method of defense while camping in the woods or something
Water - Fear of water is extremely common. Hell, my entire mum's side of the family is afraid of water.
Grass - People don't eat grass because they are afraid of it. People also don't kneel on grass because they don't want grass stains on their clothes.
Electric - You would not like getting hit by lightning, and there would probably be much crying after it happened. Also, look at how freaked out some people get when there are thunderclouds coming their way.
Ice - People hate getting cold and are deathly afraid of frostbite/being frozen to death. That's why so many people choose not to do things like climb Mt. Everest.
Fighting - Would you have wanted to get in a ring with Mike Tyson at his prime? Enough said.
Ground - People don't roll in mud because they are afraid of getting dirty. Also, after earthquakes and sinkholes opening people usually cry.
Rock - After rock slides people usually cry. Also, stoning someone to death is considered one of the worst deaths possible, and I don't know a single person who actually wants to be stoned to death. On a side note, if you are constantly getting stoned, your life will not be as long.
Flying - Fear of flying is very common, my great grandmother was deathly afraid of it when she was alive.
Poison - Remember how kings and stuff would always have food testers? That was because they were afraid of their food being poisoned. And look at how anything remotely poisonous needs a label on it warning that it is dangerous and whatnot.
Steel - People fear gangs, mostly because they have guns and knives, which are made of steel/metal (steel represent all metal in Pokemon though).
Dragon - You wake up and there is a dragon tearing your house up. Guess what, you aren't the only thing in your bed. Fecal matter is also there, because you just scared yourself s***less.
Now the only exception here is Normal, because nobody is afraid of normal things. It's when things are abnormal that the hairs on the back of your neck stand up.