What makes a Tekken Character strong?

Mainly a question for high level-players or design professionals. I'm pursuing Tekken 7 from an academic angle and I'm finding it difficult to narrow down what makes a tekken character strong. In 2D fighters it's easy to tell a characters strengths and playstyle from the onset. Even the characters that seem less straight forward may have a style centered around a few + frame moves and corner carries that can create distressful scenarios. In each case, either overt or subtle, its easy to tell what this character is supposed to be doing most of the time. In Tekken the 3D field of play and close range melee focus make it difficult to determine a character's particular strengths, weakness, or general gameplan from an outsider standpoint. I understand mobility and thus potential for counter hit and wiff punish opportunities can be a factor but it couldn't be the only one or why make a character like Gigas or Marduk?

Tl/dr; How do you identify a characters strengths, weaknesses, and general strategy? What makes a character high tier or a bad matchup for another character?