Wedlocke
Aww... isn't that cute
Originally invented by Marriland, the Wedlocke is a clever twist on a standard Nuzlocke and is great for adding a different type of challenge to your playthrough. The original Nuzlocke rules remain:
1. A fainted Pokemon is a dead Pokemon
2. You may only catch the first Pokemon you find on each route
However... here's where the clever, romantic twist comes in. Your team MUST consist of a maximum of three of each gender (i.e. 3 male and 3 female) at any one time. Genderless Pokemon CANNOT be used (e.g. legendaries).
Each male Pokemon must form a pair with one female Pokemon (hence the term Wedlocke). A battling Pokemon may ONLY switch with its partnered Pokemon. In double battles, Pokemon may ONLY battle with their partnered Pokemon.
In the event that a Pokemon dies, its partner may NOT battle again until a new partner is found.
Optional rules can be applied - such as changing the gender rule so that Pokemon can only form a partnership with Pokemon of the SAME gender. Additionally, extra rules can be introduced where only certain Pokemon Natures are compatible.

here's an example...
From the inventor themself - here's a video explaining Wedlocke challenges by Marriland. Enjoy!