I wouldn't consider myself to have good dexterity at all but have been able to play fighting games and work my way up the ranked ladder. I'd say if Tekken 8 looks cool, give it a try.

The main problem with Tekken is that it doesn't really document its systems with tutorials or a manual. Fortunately, YouTube will teach you more than enough. Tekken also tends to reward legacy knowledge more than most fighting games, so you'll probably find that Tekken 7 tutorials get you farther than you expect.