>>52577661https://gamepress.gg/pokemongo/attackers-tier-listProvides a good overview of what you should be aiming to build as end game, but can also use on the way towards it.
Best stuff is things like legendaries from raids, shadows, and Mega evolutions. Particularly those that have special moves normally only available from events.
Like the main series, many Fighting and Rock types are unreasonably good at what they do.
Offensively some Pokémon aren't gonna be relevant for raiding. You can have the most perfect bug type in the game, but they literally only matter for Hoopa Unbound raids right now.
The current fighting type event makes Machop plenty accessible though. If you have trading buddies (or a second account and device), catch a bunch of Machop and trade them back and forth until you get a couple good luckies, and some candy XL as well.
Machoke received in a trade evolve into Machamp for free, saving you 100 candy.
Machamp is a core raid battler for new players as it's more accessible, and currently Go Rocket Leader Cliff is giving out Shadow Machop. If you get one with reasonably good IVs (doesn't have to max or perfect), invest in it when you're allowed to remove Frustration. Consider purifying a dud and self-trading as your daily special trade if you're multi-accounting, because a lucky purified Machop will be super cheap to power up, like 60% less stardust and 10% less candy / XL needed.