NIDONKING- Not a sweeper why? welll for starters (i wanted to say that sorry! XD) all of its stats are barely not the same and they all stand in between 140 (lowest) to 270 (also lowest)
I wont recomend to chamge it neither because it covers a few of your other two Pokemons weaknesses.
ELECTABUZZ-This guy has more Special attack than fisical so it would be considered a special swepeer? BUT what happens if he has more fisical attacks than special? you can always change them, If you want it to be stronger evolve him into an electrivire this guy has a bunch of fisical attack , so I would recomend changing him into electrivire in this case
HERACROSS-SWEEPER this guy man this guy when you trained it you didnt THINK it would be a strong Pokemon you KNEW if you make a Pokemon party of sweepers that doesnt have a heracross that party is incomplete so about this guy its a good option to stay with it