lol, you listed ALL the ways to make a Pokemon hate you.
- making the Pokemon faint
- putting it in the PC
- using Energy Powder, Heal Powder, Revival Herb, and Energy Root
(And the last way... it doesn't really make a Pokemon hate you, it just resets the Pokemon's happiness to its base.)
So, I guess the fastest way combining all those other steps would be to level it up to the desired level you want it at. Then trade it away and then back to reset its happiness. Go into battle with the Pokemon and KILL ITTTT. Every single time. And every time it faints, use a Revival Herb on it after. And you can put it into the PC whenever you are going to have real battles and proceed in the game. Or you don't even have to put the Pokemon into the PC at all. You could just do the battling, fainting, and reviving process over and over again.