I am writing a fight scene between two monsters. One is heavily armored but comparatively slower, whereas the other is a Lightning Bruiser: fast, tough, and powerful but compared to the first character is relatively frailer and quicker, even though by most standards they would be very tough and can definitely take hits well. A good comparison might be a video game or tabletop RPG analogy: both have very high amounts of "skill points" but the former put more of them in defense and less in speed, whereas the other is equal across the board. Another analogy might be Thanos versus Hulk in Infinity War: Hulk is bigger and has more raw power but Thanos has speed and skill, albeit in this case it's not a one-sided Worf effect as in Infinity War
There are several prior fight scenes between the big, armored character and a much frailer but more nimble opponent. I know how to write these: having the frailer fighter dart out of the way of the bigger character's blows and pepper them with hit and run attacks to avoid getting hit with the one good blow that would end the fight instantly. However, I've been having trouble writing fight scenes with a character who is more durable, but simply less so than the armored character. The issue with this is I am trying to establish in these scenes that the Lightning Bruiser is a credible threat who can fight with the armored character on equal footing to raise the stakes of the fight, rather than the armored character easily overpower.
The problem is that in practice the fight seems to play out exactly the same, the less armored Lightning Bruiser ducks and darts around the blows of the more armored one, even though in practice this character is a lot tougher and a lot more powerful than previous foes. The two characters are supposed to be on an equal footing, even if their "stat distribution" is different. This creates an issue in that it gives the impression to the reader that the Lightning Bruiser is not a threat to the armored character and is exactly the same as the previous foes they faced, and overall makes the fight scenes come across as repetitive or boring.
Given this, how do I write a fight scene such that it highlights that a Lightning Bruiser character is strong, fast, and tough, and that this character presents a legitimate threat to the armored one that can fight them on equal footing.