Special Flag: When used, the character will hold it into the air and become immobile for 3 seconds the successful completion of it's use will add a point to the user's score (timed match), or give the user an additional stock (stock match).
This can be avoided by mashing buttons to escape.
Boss Galaga: When thrown, Boss Galaga will fly to the top of the screen and dive down and home in on the targeted player's position and fires it's tractor beam, catching the character by it and flies off-screen to the top of the screen.
Their attacks even become more powerful as other characters become blue and vulnerable.
Power Pellet: Makes the character who picks it invincible for 5 seconds.
All for One (My Hero Academia/Boku no Hero Academia).
Dio Brando (JoJo's Bizarre Adventure Final Boss).
Manus, Father of the Abyss (Dark Souls True Final Boss).