Do double/multi battles give reduced EXP?

[AwesomeToadUltimate]

I have been considering and testing the progression (I'm just battling the number of trainers between each gym in debug mode) between gyms in my game and I'm wondering about the progression between the fifth and sixth gyms. The fifth gym leader's Pokemon are Lv30-31. There is a water route and then Route 8, and the trainers on the water route are optional. On Route 8, there is a rival battle, with her Pokemon being Lv29-31. After that, she becomes a partner trainer, and the two of you go into the evil team's base. There are grunts in there that you fight, with their Pokemon being in the high Lv20s-low 30s. Then, you fight an admin, and I'm trying to decide if the admin would be fought in a single or double battle, but the admin's Pokemon are Lv31-33. After that, the evil team leader would be battled in a single battle, with her Pokemon being Lv32-34. Finally, there would be the sixth gym, with the gym leader's Pokemon being Lv34-36. Do double/multi battles give reduced EXP, and would this be good progression or not, and if it's not, how could I avoid raising the levels?