Silhouette Mirage: Enemies in this game display either of the two attributes, Silhouette and Mirage. Silhouette-attribute energy is harmful to Mirage enemies and vice versa.
You fight Delia, a Mirage boss, in a room where the two are out of reach of each other. The only thing he does is fill his mana meter by inhaling the Mirage soup in the huge pot and use a long-range special attack. And the only way to damage him is to poison the soup by chucking Silhouette cooks into the soup.
Gargantuan gathers energy by absorbing same-attribute matter from the outside. If it absorbs matter with different attributes, it will take damage and change its attribute. The player character wonders where to find the "matter", but as soon as the battle begins, mooks of the both attributes start appearing...
Geluve has the ability to possess mooks and use them as her "arms". The only way to do damage to her is to blast her arms. The game has a Game-Breaking Bug in which she will not summon new mooks.
In Devil May Cry 4, Mission 9 has The Containment Room. The "boss" is the glass which separates you and Agnus, and the mooks are Gladius—basically Flying Lizard Swords. You can go ahead and attack the glass itself, but you will do very little damage. the trick here is grab the critters with Buster and aim at the glass to throw it there.
The SNES version of Teenage Mutant Ninja Turtles: Turtles In Time features a boss battle like this, against Shredder, at the end of the Technodrome level. Shredder sits safely in the cockpit of a crab canon, where the turtles can't reach him. So they chuck his own soldiers at him, literally reducing them to canon fodder.
Recettear features several bosses that end up having mooks as their main downfall.
Reginald Drisby has bulking defenses when he normally runs around and attacks. Throughout the fight, Reginald will try to eat mushrooms to recover his HP. Red ones only benefit him. Purple ones, however, will leave him fallen and weak to attacks. Justified in that the mooks do heal him, and that his recovering HP strategy makes him very hard to defeat, if not take a very long time.
Volcanicrab will literally take no damage from any of your attacks initially. Bomb mooks appear eventually, however, which can flip him over to strike his underside for massive damage.
Very common in World of Warcraft. For example, Instructor Razuvious can only be defeated by Mind Controlling his disciples and using their shielding techniques to soak up his attacks. In another instance, Tortos, a giant turtle, uses a powerful breath attack every once in a while, which can only be interrupted by killing smaller turtles and then kicking their shells into the boss. When attempting Mimiron's hard mode, you "accidentially" set the entire room on fire and the boss then periodically summons Emergency Fire Bots, whose attack can kill you but also clears some of the fire, giving you room to fight. Other bosses may have adds that give you the Status Buff required to kill the boss or put a debuff on the boss so he can be damaged. There's a lot of bosses that would be unbeatable if it weren't for their Mooks.
Various games of the Yoshi's Island series have bosses that do this, all of which can be eaten to make eggs, which in turn can hurt the boss.
Super Mario 64 DS has only Yoshi as a playable character at the start. As such, he cannot punch enemies, but he can swallow them to stock up on eggs to throw. Both King Bob-omb and Goomboss could not be beaten if they did not have their respective mooks to fuel Yoshi for eggs. If anyone other than Yoshi fights Goomboss, the fight will be slightly different in that you have to punch Goombas into Goomboss in order to hurt him.
Super Mario Galaxy and Super Mario Galaxy 2 features the Bouldergeist, a ghost that encases itself within stone. Normally it would be invincible to Mario's attacks. However, during the fight it will occasionally throw a black rock at Mario, which will become a Bomb Boo, which in turn Mario can use against the Bouldergeist to break apart his stone casing. When it reaches its vulnerable phase, guess what it still intentionally spawns?
Super Mario World: The only way to hurt Bowser is to kick the Mecha Koopas he sends out up so they land on his head. Furthermore, you can pick up and throw Goombas, Mechakoopas, Buzzy Beetles and Koopa Troopa shells at any other regular Mook to kill them.
Wario World: The Angler Mangler miniboss is completely invulnerable save for its lure, which dangles out of reach. Thr trick is to wait for it to summon a Barrel Buster mook, stun it, and do a Spinning Piledriver under the lure, which sends it flying up, hitting the lure.
For obvious reasons, the Kirby games frequently feature bosses that spawn mooks for the player to hurl back at them using Kirby's default powers, most notably Kracko. Some of the games where Kirby steals enemies' abilities use a variant in which some bosses that spawn enemies with especially suitable powers. However, there are plenty of subversions featuring bosses who spawn mooks that give the player useless powers like Sleep or powers that are utterly ineffective in that particular battle.
Kirby's bread and butter abilities include inhaling an enemy and spitting it to another (when he doesn't copy that enemy).
In Mega Man 7's Wily Stages, one mthod for defeating the turtle tank boss involves using the Danger Wrap weapon to bounce its mini-turtle mooks into is beak For Massive Damage. However, most players find it more practical to defeat the boss more conventionally.
Mega Man ZX Advent: A partial example - Hedgeshock can summon robot mouse flunkies. He can normally be hurt by anything, but there's an achievement for using nothing but the mouse flunkies to hurt her - by knocking them at her with the right powerup.
The fan game Mushroom Kingdom Fusion occasionally offers variants of its source games' bosses who veer into this, such as a version of Mouser who tosses Bob-omb enemies or a variant of King Totomesu with lots of hit points and an unusual vulnerability to the exploding Koopa variants that spawn endlessly during the battle.
In the Darkwing Duck NES game, Moliarity will always leap to a different tier of the arena to prevent the player from shooting him. However, if the player to disable his flamethrower tower enemies, the usually evasive Moliarity will arrive to fix the device, giving the player an opportunity to take potshots at him for as long as the repairs take.
Some of the bosses in Zuma's Revenge are like this. The only way you can kill the boss is to damage the mooks.
Mischief Makers: Your only attack is throwing. A bit different in that instead of throwing mooks at the boss... You just chuck the boss, the boss's weapons, it's projectiles or it's own FISTS at it . The Climax Boss has you throw nice phrases at it for some reason. You have to find the right ones, shake em to turn em nice, and chuck it.
In Call Of Cthulhu: Dark Corners Of The Earth, the last boss Mother Hydra can only be defeated by mind controlling one of the Deep Ones that are spawned in the area and using the creature to damage her, then repeat the procedure multiple times until she's defeated.
This is an option in Fallout 2. You can convince the Enclave soldiers accompanying the final boss, the cyborg super mutant Frank Horrigan, to turn on him. Also you can reprogram the robot turrets that surround Frank to do the same. Useful for a Pacifist Run and otherwise.
Five hats means that five tropers think it is ready to publish.
You are saying that you think this draft is ready to be published. That means the description is not ambiguous,
it doesn't duplicate an existing trope, there are at least three examples, and the title makes sense.
Is that what you meant to do?
You are saying this draft has a ready-to-publish hat it does not deserve and you are taking it back.