It sounds like you might have some good advice for me, so I would like to ask you to be more specific: which cards are overpowered, and in what aspect/s? I have already decreased their power in relation to the more powerful Normal (and sometimes Effect) Monsters of which I am aware (such as Blue Eyes, Black Magician, and Buster Blade for Level-

. For Level-4 monsters I usually end up using Silent Magician, Skilled Light Magician, and Skilled Dark Magician as my markers.
What really does it is that most of the avengers are peak-human, if not beyond-peak-human physically, so they have to be really strong. The only ones I was able to get below that were the SHIELD agents Maria Hill and Sharon Carter (Secret Avengers), both of whom are unpowered. I also let the character's nature (ie: aggressive or cautious) dictate whether ATK or DEF was higher.
All effects reflect what the characters can actually do. The trick was finding a way to say it so there would not be so much text the size would shrink. I think I did a good job on that aspect.
I probably work from a different definition for Spells and Traps. To me Spells usually use some form of energy, although they don't always have to. Traps are mechanical, or set up ahead of time, like many of Negi's strategic plays in the
Negima manga.
In any case, if you could offer some more specific advice I would really appreciate it. Despite having created many cards I still have much to learn, but I can only do so if people give me the same sort of specific advice I have been trying to give others.
Thank you for your comments so far.