The 1st gym
Roxxane,a Rock Type leader.....
Suggested Pokemon/types = grass(treecko/shroomish)/water(mudkip/wingull)
Suggested Levels around 10 will be good...
The 2nd gym
Brawly,the Fighting type leader.....
Suggested types/pokemon = Flying (Taillow),Psychic(Ralts/Abra/Kadabra)
Suggested levels = above 17 will make the gym a cake
The 3rd gym
Wattson, the Electric Type leader
Suggested types/pokemon = Ground(Marshstomp+ ground type attack {mud slap})It alone should be enough :)
suggested levels above 25 should be good,and make your Pokemon hold cheri-berries
Moving on to the 4th gym
Flannery, the Fire type leader
Suggested types/pokemon = Water/Ground ( {azu}marill/Marshtomp)
Suggested levels = above 27 should be enough
The 5th gym
Norman(Dad),the Normal type leader
Suggested types/pokemon = Fighting (Breloom/Makuhita)
Suggested levels = above 31-32
The 6th gym
Winona,the Flying type leader
Suggested type/pokemon = Electric/Ice (Electrode/Swampert + Ice Beam)
Suggested levels = around 35
The 7th gym
Liza & Tate, the Psychic type leaderS
Suggested types/pokemon = Dark/Ghost = (Sableye/Shuppet + Shadow Ball)
Suggested levels = around 40-42 will be nice
and Finally,the 8th gym!
Juan, the Water type Master!
Suggested types/pokemon = Grass/Electric (Sceptile,Electrode)
Suggested levels = above 45-46