Help on Training!

Welp, i reached finally the Pokemon League, but i beleive my Pokemon level are too Low (45 average)

Any tips on training?
Where?
Im looking to reach level 54/55 average.

Team:

Gengar Lv 45, Moveset:
Psychic
Hypnosis
Curse
Shadow Ball

Arcanine Lv 45, Moveset:
Flamethrower
Fire Blast
Bite
Flame Wheel

Venusaur Lv 45, Moveset:
Sleep Powder
Cut (I beleive im going to replace it for Solar Beam, and then get a Cut slave)
Frenzy Plant
Razor Leaf

Dragonite Lv 45, Moveset:
Fly
Earthquake
Blizzard
Surf

Jolteon Lv 46, Moveset:
Shock Wave
Shadow Ball
Thunder Wave
Quick Attack

Machamp Lv 46, Moveset:
Brick Break
Low Kick
Strength
Rock Slide

Where do i train at? Thanks.