Here's how I see it:
refers to any fight between identical or equivalent characters. This can include clones, doppelgangers, Evil Twins, alternate universe counterparts, mimics, Enemy Withouts, and other such things. Looking similar and having the same powers are requirements here.
is a videogame-specific trope referring to a boss character with similar powers and abilities as the player character. This can overlap with Mirror Match. This does not require looking alike, just having the same powers and attacks. King Dedede is a Mirror Boss to Kirby. The Boss is a Mirror Boss to Naked Snake. Wario is a Mirror Boss to Mario. But none of them are Mirror Matches, since they're not the same character.
An Evil Counterpart
is a character who is similar to another but evil. This can include similar powers and abilities, or serving in an equivalent role in an opposing organization, or having a similar backstory. This can overlap with Mirror Match.
Superman vs. Ultraman is a Mirror Match, as they are the same character from different worlds, and Ultraman is also an Evil Counterpart.
She-Hulk vs. Red She-Hulk is not a Mirror Match, but Red She-Hulk is an Evil Counterpart, as they're different people.
Erza Scarlet vs. Erza Knightwalker is a Mirror Match with an Evil Counterpart. Same character from different worlds.
Captain Marvel — er, "Shazam" — vs. Black Adam is not a Mirror Match, but Black Adam is an Evil Counterpart.
Kasumi vs. Kasumi Alpha from Dead or Alive is a Mirror Match, Mirror Boss, Evil Twin, and Evil Counterpart. Alpha-152, however, is none of these.
An Evil Knockoff
is a copy of a hero created by a villain for the specific purpose of fighting that hero. These can also be Mirror Matches and Mirror Bosses.
Note that Mirror Boss, Evil Counterpart, Evil Knockoff, and Evil Twin refer to the character, while Mirror Match refers to the fight.