How about we talk about Assist Trophies? Most assist trophies are main characters of unrepresented franchises or secondary characters from represented franchises, but many fall into a third group. Regular enemies.
As of now, Smash only has 12.
Burrowing Snagret (Pikmin)
Chain Chomp (Super Mario)
Chef Kawasaki (Kirby)
Ghosts (Pac-Man)
Hammer Bro (Super Mario)
Klaptrap (Donkey Kong)
Knuckle Joe (Kirby)
Lakitu and Spinies (Super Mario)
Metroid (Metroid)
Rathalos (Monster Hunter)
Starman (Earthbound)
Thwomp (Super Mario)
Lakitu and Spinies got cut sadly.
What are some regular enemies you think would make fun assist trophies?
Polar Bear (Ice Climber): Acts like it did in Smash Run, walking around and occasionally jumping to make a huge earthquake. Can be defeated, and has a special weakness to flame attacks.
Creeper (Minecraft): Walks towards the nearest player and explodes, dealing massive damage and knockback, even to the player that summoned it. Think a slightly more mobile Electrode. Can be defeated, which causes it to detonate instantly. When this happens, whoever dealt the final blow is immune to the explosion.
Slammin' Lid (Splatoon): Spawns Chums, Smallfries and the occasional Cohock. Slams down on players that get too close. Its aircraft acts as a platform, on which players can jump on and attack the pilot.
Metal Slime (Dragon Quest): Runs around the stage, weakly ramming into opponents dodging any attacks that come its way, while also reflecting any projectiles. If it is defeated, whoever did so temporarily "levels up" and gains a substantial power boost for a couple of seconds.
Also, have some minibosses that would make good Assist Trophies.
Boom Boom (Mario): Runs around, wildly swinging his fists. While he's swinging, he is immune to all attacks from the side. Jumping on his head stuns him and leaves him vulnerable. Can be defeated.
Lynel (Legend of Zelda): Based on its Breath of the Wild appearance, this vicious monster attacks with a Lynel Sword and Bow, while also breathing fireballs. Can be defeated... with great difficulty.