Standard plot of DBZ: "This is the strongest opponent we've ever faced." *get strong enough to beat them* (a few episodes later) "Ok, THIS is the strongest opponent we've ever faced." *rinse and repeat*. Using this guide, Goten.
Fanboy, it can depend on the context of your words. It can simply mean you're a fan of that character and highly knowledgeable of that character, but based on your question. You're asking for the term fanboy to be defined in the term of an insult. Which you pretty much sum it up. But to help back you up here.
It's someone who pretty much will speak on behalf of a character they like so much that any form of defeat of the character can not be accepted, comprehended, or understood. It doesn't matter how much logic or reason you use, this will not go through. At the same time, they try to provide feats they can't provide or provide feats and take them out of context to seem much more "powerful" than what is shown. They will take the concept of the character that's written on paper and exaggerate to such a degree, that's it not even the same character. They will sum up the character or give the impression the character is "All Powerful and Godly"
This. Plus, you can probably find a fanboy in any one of the threads that involves a controversial character, such as hulk, dd, TOAA(just kidding), or someone like that. Thank you for giving me the chance to see this once more, and special thanks to Charmix for reminding me having me dig this up. It's the seven stages of fanism.