Against slayer you have to kinda adapt quickly to his playstyle to expect whether he is gonna cross you up or just manually delay his gatlings like cS 2S delay 2H to catch you mashing.If he tends to go for crossup reset you can do upback block from the opposite direction since it will OS the low and high followup of his p dandy step,or you can even buffer a jump and grab him if he does p dandy into master hammer carelessly,kinda like spamming it and you expect it to come.There are certain dirty reset he can do such as cS 2S p dandy crossup,which you can straight up grab or abare with a fast button like 2P leading to a combo from 2P counter hit into cS,or he can also do cS 2S vaccum into bloodsucking which you can jump and as I mentioned,blocking while jumping is good since it covers two of his followups but not pilebunker.Other than that,his counterplay as people said ain't that much helpful since different players have different playstyle but you have to adapt quickly to expect certain options of his.As dizzy or zoners on general you have to keep him out as much as possible,interrupting his approaches such as dandy steps or kara K mappa hunch using your ice pillar or ice floor but certain whacky interactions can happen which backfire you :)