Ask yourself: how did you raise happiness of pokes? By mindlesly grinding them unhumanitary way. And, theres no back side of that - you can only go up, it can only like you more, not less. I would like to present a other, more humanitare system, wich would both reward hard grinding, and actual helping your pokemons grow up.
Now there would be two possibly ways to go with hapinnes of pokemon:
Discipline - Gained by: Grinding in same area for a long time, loseing, beign forced to fight against superefective pokemon, not beign allowed to evolve, holding evolite, fighting with enemies way stronger than self, beign forced to fight while having low hp. All those make happines value lower and lower till they fall down to max wich is Discipline. Any pokemon trainted this way on the start of the route might be unobiediant but at the end will be granted with more attack of both types, and will do whatever their trainer say. Moves that require certian amount of happines will be usable, but those who actually calculate them will likley fail.
Friendship - Gained By: Winning with gym leaders, evolving, fighting with foes of near same level, having other pokemon from same type party, having other pokemon from same species but other gender in party, participating in contest (if they gonna be added), eating berries, beign interacted with, walking with trainer, holding soothie bell, fighting in area where it was catched. This route bulids trust between pokemon and trainer, on max granting Friendship. Pokemon that like you, will likley be most determinated ones, as they will slowly regenerate each turn even from gratest scars. Not only that - they may also tell about you other pokemons, wich more likley will let catch themselfs.
