What you need:
A poke high lv with false swipe move( like Parasect for example he can learn with a tm)
Poke low lv with a priority move(eevee with quick atack for example).
What you will do:
Go to a place with high lv wild pokes(Dragons Den for example), find one and use false swipe move and left the wild poke with 1 hp, left the false swiper move die, change to the poke low lv with the priority move and use that move.
Some hints
If you choose parasect as your false swipe user, find a golbat at dragon dens he can kill parasect fast and you just need 1 or 2 false swipe to let him with 1 hp.
You can bring with you some revives/potions to use on your false swipe user to up even more faster.
Good luck and sorry for my bad english :Angel: