Can anyone give me their thoughts and suggestions on my current platinum team?

This is my team. I've just defeated the first gym

TEAM:

Turtwig (My starter)
Level: 15
Type: Grass
Nature: Hasty
HP: 42
Attack: 27
Defense: 23
SP. Attack: 22
SP. Def: 22
Speed: 18
Ability: Overgrow
Moves: Tackle, Withdraw, Absorb, Razor Leaf

Ponyta (My fire pokemon. If i find any better fire types, i might replace her)
Level: 14
Type: Fire
Nature: Adamant
HP: 42
Attack: 33
Defense: 23
SP. Attack: 21
SP. Defense: 24
Speed: 30
Ability: Run Away
Moves: Growl, Tackle, Tail Whip, Ember

Staravia (My flying transport)
Level: 14
Type: Normal/Flying
Nature: Rash
HP: 42
Attack: 26
Defense: 22
Sp. Attack: 18
Sp. Defense: 15
Speed: 29
Ability: Intimidate
Moves: Tackle, Double Team, Quick Attack, Wing Attack

Shinx (A Electric pokemon that i'm currently debating to either keep further on or replace it with a stronger pokemon)
Level: 14
Type: Electric
Nature: Docile
HP: 40
Attack: 27
Defense: 17
Sp. Attack: 17
Sp. Defense: 15
Speed: 18
Ability: Intimidate
Moves: Tackle, Leer, Charge, Spark

Bidoof (Team placeholder. I'm going to replace it with a stronger pokemon later on)
Level: 14
Type: Normal
Nature: Hardy
HP: 41
Attack: 18
Defense: 19
Sp. Attack: 16
Sp. Defense: 16
Speed: 17
Ability: Simple
Moves: Tackle, Rock Smash, Defense Curl, Rollout

Beautifly (Yet another placeholder)
Level: 14
Type: Bug/Flying
Nature: Hasty
HP: 42
Attack: 28
Defense: 20
Sp. Attack: 33
Sp. Defense: 20
Speed: 26
Ability: Swarm
Moves: Tackle, Gust, Poison Sting, Absorb.



Any suggestions, such as what pokemon to get later on in the game, will be helpful.