Question

Is Gible a good Pokemon to train in Pokemon diamond?

Answer 1

Yes.

Garchomp is easily worth it - even if you're using Dialga on your team, it's still a good investment. Gible learns Dragon Rage at level 7 - I can't remember exactly how early you can catch one, but Dragon Rage in early game is ruthless. Garchomp boasts a very nice movepool including STAB Earthquake and Outrage (You can also teach it 5 out of 8 HM moves if you need HM coverage, or Swords Dance and False Swipe to assist in capturing legendaries.) It reaches its final evolution at level 48, so it should be fully evolved before the Elite Four.

Comments

you can catch one in wayward cave, under the bicycle path

Answer 2

Gible is definitely a good Pokemon to train in Diamond, evolving to Garchomp
If you were to consider training Gible, here is a moveset to work on;

Garchomp @Leftovers
Trait: Rough Skin
Jolly Nature (+Spd, -SAtk)
EVs: 252 Atk / 252 Spe / 4 Def

Moves:
- Earthquake - STAB
- Stone Edge - Type Coverage
- Dragon Claw - STAB
- Sword Dance - Boost Attack