Torterra 348 atack :)
Infernape 337 atack :p
Empoleon 298 :o
Tepig.
Well if you take a squartile (or that's how you spell it) your rival will take bulbasaur and if you take a pidgey and teach it wing attack and gust and deafiting kene is easy. Deafting brock is easy if you have a squartile or a bulbusaur. I suggest you go with squartile.
No you can not find TM. thunderbolt in the power plant. Sorry. But you can the second most powerful electric attack there, Thunder, along with the Legendary Pokemon Zapdos.
Most dark types or normal types.
there is no universally good starter in leafgreen/firered, but the most convenient one is squirtle-with good training, it will beat the first gym leader, brock, singlehandedly. your nemesis will choose the Pokemon with the obvious upper hand in types against yours, so if you chose squirtle, your nemesis will have bulbasaur. a good way to defeat it, i found, is to keep a strong fire Pokemon, like arcanine, ninetales, or moltres, handy when you battle that person.
dialga dialga is not a starter Pokemon. if anyone does know the starter Pokemon that appears the most in the game heart gold and soulsilver please answer. maybe you spelled the name wrong or were thinking of another Pokemon.
mudkip is the most powerful
Pretty much most bug, grass, and poison types can.
fire type chimchar
yes. in all Pokemon games (or all the ones ive played) Pokemon evolve. But not every Pokemon evolves most do tho.
Tepig
You cannot 'finish' Pokemon LeafGreen and FireRed. You might be thinking about defeating the Elite Four. That is the end point of most trainers, but you can go ahead and capture legendary Pokemon like Mewtwo, Lugia and so-on.