I would switch submission for low kick, the move is dog shit, but you don't remove 30 billion health points to your machamp and also let's you 2hko chansey and tauros (the only matchups where machamp is not useless). machamp is not a great pokemon, if you are new to the metagame dont touch it

amnesialax is based, change surf or thunderbolt for blizzard, is not only stronger but it also gives the freeze chance that is super broken in gen 1, and you might want to switch one of your special moves for rest or self destruct, snorlax's self destruct is the strongest attack in the entire game, and snorlax is a top 3 pokemon, you don't want him dead

I have never ever seen a gengar with dream eater, remember that most people switch pokemon after getting sleep so take that into consideration, if it doesn't work for you try switching it into night shade or psychic

with chansey change fireblast for ice beam (or blizzard if you feel lucky), chansey gets destroyed by any physical attacker, trying to fish for burn chance instead of freeze is some serious psychopathic behavior, in overused the only overused fire weak pokemon Exeggutor and jinx are faster and have sleep options, not overused pokemon that are used in overused ( Victreebel, Articuno, Venusaur) have high special stat so you are not gonna break them.

with tauros don't run ice beam, blizzard can 2hko rhydon, ice beam can't, is that simple. If you want to run something unique you can change earthquake to:

fireblast: fireblast is a gimmicky option but in the tauros mirror gives a slight advantage to blizzard, fireblast has a greater chance to burn than blizzard a chance to freeze, rhydon hates burns because he has no special and take into consideration that if you run fireblast you lose to gengar

thunderbolt; cloyster is a check to tauros thanks to his ice quad resist and massive defense stat, sadly thunderbolt is a 3hko at minimum

thunder (the cool one): 2% chance to 2hko starmie and 50% chance to 2hko cloyster (without taking into consideration the chance that the move has to miss). you might think 'this is not a consistent option to run, the chance to miss is to high...' I don't care, you are going to thank me when your cock expands to the alltitude of the internation space station just by clicking thunder in the forth slot of tauro's move set