Pretty much any character can work in the right team. The overall game system plays a large part in matches - basically, in a game like SF or GG the character matchup dictates a lot about how the match plays out. In KOF13, it’s more that the meat is the universal movement system and hop pressure and the characters are a heavy dose of seasoning around it.
Pretty much every character also has some scary stuff, the top tiers obviously more of it and/or more evil stuff.
The big thing going for the top tiers in this game is not that they’re way beyond everyone else, but that they’re top tier in every slot. Like, EX Iori is clearly a better than Duo Lon (a top point character), but not that much if both are played on point. Duo however sucks as an anchor because he can’t turn meter into damage that effectively. He has an insane meterless game and can solidify it further with a little bit, but that’s it. Iori has an insane meterless game AND can turn a lot of meter into a dead character a-ok. So the primary thing you have to look for when building lower-tier teams is the team order so each character is doing a job they can do well. I can just choose any three from EX Iori, Karate, Kim and Benimaru, put them in any order I wish and have a viable team. Duo Lon/Takuma/Vice is quite competitive with that, but stuck in it’s team order because of character specialization.
The lower tier characters are noticeably, clearly inferior, but the tiers are pretty compressed if characters are doing their jobs. People like to say this game is Marvel and Karate’s Vergil and stuff. They’re wrong. Other people like to say the tiers don’t matter and differences are almost irrelevant. They’re wrong too. “Character X is pretty good” is a true statement for pretty much every character.
What character(s) are you looking to play?