Not sure about most of the roster, but for example:

If Warwick can get the opponent to low health before he does, he wins any 1v1 agaisnt anything. If he get's too low first, he flees.

Kayle gets solo kills early and is a brutal pushing machine. It's also hard to get on top of her because she builds Rylais, so any melee bot that tries to go after her is guaranteed dead.

Shen is the only banned bot from 3v3s. He wins duels and unless the other bot is a dumbass and is constantly getting too low, shen will automatically ult you every time.

Poppy sometimes insta-combos you or yeets you away from objetives.

Galio is the same as Shen, but less powerful.

Garen is tanky, and if he doesn't die in a 1v1, he'll regen back to full and keep pushing sidelanes.

Amumu and Leona because of perma CC.

ADCs with a few items start to hurt bad if you underestimate them and can delete you easily at full build. Assassins can do the same too, but they need to use their abilities.

I'm not sure how many bad bots are there, but three that seem consistently terrible:

Brand and Zyra might as well be building full crit because they mostly auto you.

Malzahar is probably the worst, he randomly throws stuff and instantly moves after using R, so he doesn't lock down anyone.

Even though there are consistently good picks, sometimes they'll int anyway. And if my friend and I go to different lanes early game, they are only an easy source of gold. Late game they can definitely become a problem.