First off, Building a Wriggles lantern is completely pointless on Renekton, CDR is tons better for him, especially early game.
Garen which I'm pretty sure has health pots and boots because he's so confident of his PASSIVE.
Tryndamere is related to Renekton, he has a fury bar just LIKE RENEKTON, also the Fury bar for Tryndamere was actually a buff with his Demon Blade skin.
Renenkton does not dominate against these champions, they're actually all equal, and they all have a better passives than him.
Shyvana after she gets wriggles becomes better than Renekton, Garen becomes better than Renekton after getting many health pots, also if Garen is smart and silences at the right time, he can kill Renekton and use his ultimate to kill Renekton. Lastly, Renekton does beat Tryndamere top, but tryndamere usually runs like a ***** before he gets killed then tower hugs till he gets his ult.