Tryndamere doesn't seem to be this champion because of teemo, quinn, kennen, a good jax, etc. Would it be someone like kennen because of his teamfighting ability and safe farming? I would assume the champion needs to be ranged so the champ can safely farm, but it needs some good carry potential.
All comments appreciated.
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Both Mid and Top.
He takes a lot of practice, but he can lane safely into any match-up if you know how to play it, and can even afford early aggression into his worse match-ups.
The only one I really have problems working around is vs Irelia.
If you are good enough any champion can do well in any situation. For example, BoxBox plays Riven into her hardest counters and wins just by playing better. However if you are looking for the champion with the least counterplay it is currently Jayce top lane. And you will have to be a meta slave as such champions get nerfed or fall out of meta, replaced by others.
I instead suggest picking a main, and having a nice little pool of backups, and/or a couple supports. Learning those well, and playing them according to need.
Depends on which position you're looking at. Top can find Renekton, Darius, and Irelia doing well. Mid has Ryze, LeBlanc, and Ahri. Bot lane is Twitch, Caitlyn, and Vayne. Jungle has Twitch, Kha'Zix, and Rengar.
I'd say any champ who is viewed to have a higher skill cap than most. I'd say Yasuo, Riven, and Zed.
I might be biased but I would have to say 
. I think THE only matchup I have NEVER won to date is vs a 
... Although you don't see him often, he just plain outscales Irelia till teamfights.
I also HATE laning vs these two but the lane is entirely winnable.
PS: don't ban Darius when you play Irelia. Just dumpster him in lane. When he Q's, Bladesurge on him so he doesn't heal, then just out trade him with W and E.
None. You can't always carry when behind a lot. But you can contribute enough for a win nontheless.
The hated champions 
Also some if you master give great results 
