Charizard

Even in previous generations, Charizard was known as a very threatening Pokemon. Charizard is very versatile with balanced offenses, a large movepool, and great Speed, which all allow it to run a vast variety of sets. For that reason, Charizard is mostly seen on offensive teams, including but not limited to sun teams where its Fire-type attacks are much more powerful. Its 4x weakness to Stealth Rock can hinder its ability to sweep, but it can also work to Charizard's advantage, bringing it into Blaze range quickly. With such great power and versatility, it's safe to say that Charizard is the strongest Fire-type Pokemon in NU.