Are all Champions Viable?

For TL:DR, go down past the =

When I think of League of Legends, I see a diverse cast of characters with different abilities and potential. However, the "meta" as it is seems to favor some champions over others which I feel is a bit meh. Let's look at a few examples.

Fiddlesticks has been in League for a very long time, but his status as the years progressed has him dropped rather significantly. Compared to the champions like etc (feel free to add to it), he's been mostly put on the backburner by people. Viability in comparison, Fiddlesticks is low compared to the others.

Here's a champion that is rarely if ever seen. Typically he could be considered a top laner, but in the face of champions like , he just isn't up to snuff.

I really like this guy's concept. His potential is HUGE, but in the face of champions equally tanky like etc, he just isn't as good.

For a final example, take . Started strong, but the balance was called for and now he's just been sitting down and doing nothing.

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The main question is this: Can Champions like Fiddlesticks, Urgot, Mordekaiser, and Aatrox be viable competitively, or will they continue to be ignored in favor of the hypothetical "stronger" champions.

If an expert Urgot went against an expert Darius, who'd win? I'd like to say 50-50 chance but that just isn't the case as much.