i think it is machop.
There is no official Pokemon game that has all Pokemon catchable in it, which means you'll have to trade and transfer Pokemon from other games to get all the Pokemon. However, some fan-made hacks do have all the Pokemon catchable in them.
More than 495, 493 currently catchable in games. The other two are 5th Gen, Zorua and Zoroark.
Yes in Mystery dungeon you're the Pokemon!
Bagon is not catchable in Diamond. You can get it in Platinum and Pearl by using your PokeRadar at the northern part of Route 210. You can also migrate it from the GBA games.
Passimian is a Fighting type, and it was introduced in the Generation 7 games, Pokemon Sun and Pokemon Moon.
Crabrawler is a Fighting type, and it was introduced in the Generation 7 games, Pokemon Sun and Pokemon Moon.
Of course in certain games its catchable like in gold, silver and crystal, some games get it via event like firered and leafgreen. You can also get a ho-oh in Pokemon colosseum.
fighting type pokemons weakness are psychic and flying moves steel is weak aageinst water fire fighting and ground
Bewear is a Normal-Fighting type, and it was introduced in the Generation 7 games, Pokemon Sun and Pokemon Moon. The evolution path for Bewear is Stufful (Normal-Fighting) >>> Bewear (Normal-Fighting).
Stufful is a Normal-Fighting type, and it was introduced in the Generation 7 games, Pokemon Sun and Pokemon Moon. The evolution path for Stufful is Stufful (Normal-Fighting) >>> Bewear (Normal-Fighting).
Marshadow is a Fighting-Ghost type, and it was introduced in the Generation 7 games, Pokemon Sun and Pokemon Moon. Marshadow is a Mythical Pokemon.
Bagon is indeed a rare Pokemon. In most games Bagon is only catchable near the end of the game or after defeating the Elite Four or getting the National Dex. The only exception is Pokemon X and Y were it can be caught rather early in Route 8 though is still very rare.