How is damaged calculated?

[Luthien]

So, I'm training a Tyrannitar.
His starts:

Nature: Adamant
HP: 205
Level: 55
Attack: 224
Defense: 156
Sp. Atk: 103
Sp. Def: 132
Speed: 95

His attacks:

Rock Slide
Earthquake


Now, my REAL QUESTION: I want to teach him an Electric attack and a Fire attack. My real problem is that I originally wanted to teach him Thunderbolt and Flamethrower.
I considered changing it for Thunder and Fire Punch because his Attack stat is really higher than the Sp. Atk.
But then my mind got really confused because each attack has a power.
Thunderbolt is a stronger attack than Thunder punch, and the same thing happens with fire.

How is the damage calculated? How does the stats affect each power of the attack?
Thanks!

 

[Typhlosionisafirebadger]

the stats increase the effectiveness of that attack. Since Tyranitar has an adamant nature, that increases his attack, but lowers his special attack. This means that if you gave him a special attack like thunderbolt, it wouldn't be as strong as say, Thunderfang/Thunderpunch. To get the most out of your tyranitar, a physical moveset is the best thing to use, esp since his attack is 100 plus points higher than his sp atk.

I wish I could tell you something better but I think this can help

 

[LadyScathach]

I know the basics of calculation, but honestly, your best bet is probably just to go to Psypoke's Damage Calculator (or anyone elses, I just prefer PsyPoke) and enter your Ttar's stats. Then select an opponent that takes both attacks at neutral damage and has the same Def and SpD (Mew or a neutral Arc are the best). Then just compare damage outputs.

 

[Ludwig]

Most pokémon you'd be using fire moves against have worse sp. def than def, so flamethower is preferred.

 

[Luthien]

But my Sp. Attack is also bad.....so, bad vs. bad seems kinda neutral. Lol

 

[Ludwig]

But my Sp. Attack is also bad.....so, bad vs. bad seems kinda neutral. Lol

It's a matter of how bad. There are only three common pokémon that a tyranitar would use a fire move against: Skarmory, forretress and ferrothorn. Skarmory and forretress have so low sp. def that a special move will be better than a physical despite the lower offensive stat. Ferrothorn have about as high defense as special defense, but flamethrower have the advantage of higher power and doesn't make contact. Overall, fire punch is better than flamethrower against ferrothorn, but is not superior when considering all three.

I recommend crunch as last move.