So, firstly the recommended team:
If you choose Torchic as the starter,
Blaziken
Walrein
Cradily
Gardevoir
Flygon/Salamence
It you choose Mudkip as the starter,
Swampert
Torkoal
Cradily
Gardevoir
Salamence
It you choose Treecko as the starter,
Sceptile
Torkoal
Walrein
Gardevoir
Flygon/Salamence
Now the guide:
First Gym Leader: Roxanne (Rock Type)
Pokemon: 2 Lv. 12 Geodude and Lv. 14 Nosepass
For Mudkip and Treecko choosers, there shouldn't be any problem but for Torchic choosers, you need to evolve it into Combusken so it learns Double Kick and kicks ass!
Second Gym Leader: Brawly (Fighting Type)
Pokemon: Lv. 16 Machop , Lv. 16 Meditite and Lv. 19 Makuhita
Ralts can take care of this gym for Treecko and Mudkip choosers but in case of Torchic, Combusken learns Peck which is very valuable here.
Third Gym Leader: Wattson (Electric Type)
Pokemon: Lv. 20 Voltorb , Lv. 22 Magneton , Lv. 20 Electrike and Lv. 24 Manectric
No starters should have any problem here, even for Mudkip since after it evolves, it gains Ground type as a secondary type. Treecko can have little problem with Magnemites and Magneton since they are Steel type too. So, for Treecko choosers, it is recommended to have a Makuhita or a Machop just in case.
Fourth Gym Leader: Flannery (Fire Type)
Pokemon: Lv. 24 Numel , Lv. 24 Slugma , Lv. 26 Camerupt and Lv. 29 Torkoal
Mudkip choosers will not have any problem facing this leader. For others, It is recommended to have a Geodude. But if you don't have it then your Kirlia should be dealing here. And an important advice: Don't use a male pokemon on Torkoal, it has Attract and it will be real pain if she does that.
Fifth Gym Leader: Norman (Normal Type)
Reward: 3100
Pokemon: Lv. 27 Spinda , Lv. 27 Vigoroth , Lv. 29 Linoone and Lv. 31 Slaking
A real pain without Fighting type.. Blaziken shouldn't have any problem here but for others, use strong special moves which Gardevoir can do as Slaking has low special defense. Rest other leave it to luck.
Sixth Gym Leader: Winona (Flying Type)
Reward: 3300
Pokemon: Lv. 29 Swablu , Lv. 29 Tropius , Lv. 30 Pelliper , Lv. 31 Skarmory , Lv. 33 Altaria
Here you should have a rock type with you (I know that you guys must be having Lileep but its quite useless unless it evolves), If not then only Gardevoir should do here (in case of Sceptile and Blaziken) or Swampert can do too.. But for Altaria, Swampert won't be that useful. Only Gardevoir can be counted on.
Seventh Gym Leader: Liza & Tate (Psychic Type)
Reward: 8400
Pokemon: Lv. 41 Claydol , Lv. 41 Xatu , Lv. 42 Solrock and Lv. 42 Lunatone
Here Sceptile and Swampert should do fine coz they use Solrock and Lunatone which are Rock/Psychic.. In case of Torchic starters, Vibrava will RAGE here! For Xatu and Claydol, you should have Sealeo with Surf by now which can easily kick their asses!
Eighth Gym Leader: Juan (E)
Reward: 4600
Pokemon: Lv. 41 Luvdisc , Lv. 41 Whiscash , Lv. 43 Sealeo , Lv. 43 Crawdaunt and Lv. 46 Kingdra
Sceptile should do fine. For others Cradily may be risky since it also has Rock type but won't be that much of a problem. Flygon can kick Kingdra's ass which normally can't be kicked.
If you choose Torchic as the starter,
Blaziken
Walrein
Cradily
Gardevoir
Flygon/Salamence
It you choose Mudkip as the starter,
Swampert
Torkoal
Cradily
Gardevoir
Salamence
It you choose Treecko as the starter,
Sceptile
Torkoal
Walrein
Gardevoir
Flygon/Salamence
Now the guide:
First Gym Leader: Roxanne (Rock Type)
Pokemon: 2 Lv. 12 Geodude and Lv. 14 Nosepass
For Mudkip and Treecko choosers, there shouldn't be any problem but for Torchic choosers, you need to evolve it into Combusken so it learns Double Kick and kicks ass!
Second Gym Leader: Brawly (Fighting Type)
Pokemon: Lv. 16 Machop , Lv. 16 Meditite and Lv. 19 Makuhita
Ralts can take care of this gym for Treecko and Mudkip choosers but in case of Torchic, Combusken learns Peck which is very valuable here.
Third Gym Leader: Wattson (Electric Type)
Pokemon: Lv. 20 Voltorb , Lv. 22 Magneton , Lv. 20 Electrike and Lv. 24 Manectric
No starters should have any problem here, even for Mudkip since after it evolves, it gains Ground type as a secondary type. Treecko can have little problem with Magnemites and Magneton since they are Steel type too. So, for Treecko choosers, it is recommended to have a Makuhita or a Machop just in case.
Fourth Gym Leader: Flannery (Fire Type)
Pokemon: Lv. 24 Numel , Lv. 24 Slugma , Lv. 26 Camerupt and Lv. 29 Torkoal
Mudkip choosers will not have any problem facing this leader. For others, It is recommended to have a Geodude. But if you don't have it then your Kirlia should be dealing here. And an important advice: Don't use a male pokemon on Torkoal, it has Attract and it will be real pain if she does that.
Fifth Gym Leader: Norman (Normal Type)
Reward: 3100
Pokemon: Lv. 27 Spinda , Lv. 27 Vigoroth , Lv. 29 Linoone and Lv. 31 Slaking
A real pain without Fighting type.. Blaziken shouldn't have any problem here but for others, use strong special moves which Gardevoir can do as Slaking has low special defense. Rest other leave it to luck.
Sixth Gym Leader: Winona (Flying Type)
Reward: 3300
Pokemon: Lv. 29 Swablu , Lv. 29 Tropius , Lv. 30 Pelliper , Lv. 31 Skarmory , Lv. 33 Altaria
Here you should have a rock type with you (I know that you guys must be having Lileep but its quite useless unless it evolves), If not then only Gardevoir should do here (in case of Sceptile and Blaziken) or Swampert can do too.. But for Altaria, Swampert won't be that useful. Only Gardevoir can be counted on.
Seventh Gym Leader: Liza & Tate (Psychic Type)
Reward: 8400
Pokemon: Lv. 41 Claydol , Lv. 41 Xatu , Lv. 42 Solrock and Lv. 42 Lunatone
Here Sceptile and Swampert should do fine coz they use Solrock and Lunatone which are Rock/Psychic.. In case of Torchic starters, Vibrava will RAGE here! For Xatu and Claydol, you should have Sealeo with Surf by now which can easily kick their asses!
Eighth Gym Leader: Juan (E)
Reward: 4600
Pokemon: Lv. 41 Luvdisc , Lv. 41 Whiscash , Lv. 43 Sealeo , Lv. 43 Crawdaunt and Lv. 46 Kingdra
Sceptile should do fine. For others Cradily may be risky since it also has Rock type but won't be that much of a problem. Flygon can kick Kingdra's ass which normally can't be kicked.