Misprints and/or Errors

New to the forum and this is my first post. I been collecting since they came out and I just got back into collecting. I want to finish a couple of sets. Anyways, I keep my best cards protected, such as holo's rares and anything of value. But I want to know which error or misprints or maybe even common cards that have value to em. I have thousands of cards im about to sort put in sets and try to complete so this is the perfect time to look for cards like these. I've also looked some up and I do have these, hp vulpix, shadowless red cheek pikachu, shadowless length length bulbasaur. I have no idea which ones are rarer then others so if you guys can help me out.

A list of the most widely known error prints that have been verified over and over is here: http://bulbapedia.bulbagarden.net/wiki/Error_cards

Of the 3 you mentioned, the Vulpix isn't valuable simply because it was fixed so late into the print run that the one that reads "50 HP" is the rare version. As for the other two, they're likely sought after, but that doesn't necessarily make them rare.

I found a Jungle Set Venomoth in my collection today that didn't have the symbol for jungle set. It's number is 13/64 that's how I figured out it was from jungle set.

I found in my collection three questionable cards.:
Unown(I) that has the ex Unseen Forces symbol and reads 1/24 and I could not find it in the card list of the set (which contains 140 some cards). It is a holo rare, has 60 hp, an ability, and one attack. (I'm not sure if it is just secret rare or not)

Picachu from DP Great Encounters. It is a reverse holo common card with a set name in the picture that reads Diamond and Pearl which does not match the set. I got it in a booster, as well. The set number is correct. There is a normal and reverse of the card, but this is my only one like this. None of the other reverses from the set have this in them.

Dialga from Platinum. This card I have many of, but one caught my eye after a while. The card, instead of being metal type like it was listed as, it is my only reverse rare dialga and has it's type as colorless. Same attacks and everything else.

These could be either misprints, secrets, or I'm just unaware. Please tell me what they are.