Well... I've updated this way too much the past few days XD
Comment which kind of room you'd like to see next!

Fusion Name: Lilleon
Nickname: Lily
Type: Grass/Fairy
Bio: These Pokémon have been best friends for the longest time, and once they encountered a near death experience, they fused to save each other's lives. This is an extremely stable fusion, with a high chance of never separating.
Owner: jirachi8

Fusion Name: Sylvenne
Nickname: None
Type: Fairy
Bio: These two Pokémon once shared a loving old lady as a trainer. Once she passed away, the two Pokémon fused out of grief and loneliness, and now constantly sabotage Pokémon showcases in hopes to attract the attention of another trainer.
Owner: MISTY_TEAM

Fusion Name: Laprius
Nickname: Lappy
Type: Water/Grass
Bio: These Pokémon both belonged to Team Aqua. They tried to escape, and almost didn't. What saved them in the end was fusing in the moment of desperation, allowing them to escape into the outside world. They most likely won't become unfused, considering the sense of security in the more powerful body of a fusion.
Owner: @s11759

(Left)
Fusion Name: Shaylia
Nickname: None
Type: Grass/Psychic
Bio: Unknown
Owner: SOFAlovesBANANAS12

(Right)
Fusion Name: Mega Zorario
Nickname: Zoro
Type: Dark/Fighting
Bio: These two Pokémon met in a mystic forest, completely inhabited by Pokémon without a trace of human life. After a while, they fell in love, and fused. They can mega evolve, and Lucario usually controls the fusion.
<Stones included>
Owner: @SilverWolf807

(Left)
Fusion Name: Mega Dianslash
Nickname: Mysticious
Type: Ghost/Steel
Bio: Long ago, these two Pokémon fought for leadership of the Kalos region, before even the huge Pokémon war. Diancie and Aegislash eventually made a truce after many years of fighting, and fused together to ensure equality and security. They can mega evolve, and usually Aegislash controls the body, and Diancie controls power and attacks.
<Stone included>
Owner: @TwinHeartStigma

(Right)
Fusion Name: Gardanna
Nickname: Winter
Type: Water/Psychic
Bio: These Pokémon originally performed alone, creating move combinations in the centers of different cities, simply for enjoyment. However, when they met in Black City, they performed together and formed a strong bond. From that point on, they travelled together, and after a while they fused in the middle of a performance.
Owner: AuraAbsolTheInkling

(Left)
Fusion Name: Altaronair
Nickname: Air
Type: Dragon/Flying
Bio: Unknown
Owner: @lunakratt

(Right)
Fusion Name: Milodeen
Nickname: Fibi
Type: Fire/Water (Yes, I know that neither of them are fire type. Roll with it.)
Bio: After Goldeen was released by its trainer into the ocean, Milotic found it, lost in the vast body of water and trying to find the entrance to the freshwater stream where it was hatched. Milotic decided to help it find its home, and in the process the two Pokémon formed a strong bond, and fusing.
Owner: Greninja_Girl