I mean-Do you have any other method for your Pokemon to gain EXP Point,aside from battling other trainers! Like Battling Wild Pokemon,which I do a lot of and especially in the beginning (because when I start my Journey I want my Pokemon to be Level 10 or higher and I always raise it up to that level before setting out...don't ask why because it's a strange habit for me.) or when my Pokemon's level is lower than the Gym I'm up to (yes that happens from time to time)..so Yes I do.

I battle wild pkemon then one of my party member holds a exp.share that's what I do usually

I battle wild Pokemons more often than battling Pokemon trainers.

Once the elite four have been defeated, I just go through them again and again, using the exp share. Also battle wild pokemon.

well, i don't feel like constantly battling wild pokemon so i just give one of my party members a rare candy. but i sometimes battle wild pokemon for exp.

I also train them by:
Day Care
Wild Pokémon
Rare Candy

^Exactly what i was going to say! And I really love Rare Candies :)

I use my exp share a lot anf i challenge wild pokemon on a regular basis

I usually use wild Pokemon,Pokerus and Macho Brace if I can be bothered battling trainers but I do use an Exp.Share as well I don't use Rare Candies or Daycare very often