@Zenpou: I have some experience at fighting a decent Slayer. There are 3 things that I've found that will keep slayer preoccupied. Net, Forward Exe, and 6k.
Slayer has a really short air dash. A backdash and 6k will probably screw up his range. If you can 6k on reaction while he's in the air, thats even better. Slayer's j.hs pretty much clashes with everything Testament has in my case. Including Nightmare Circular. I find this pretty annoying.
Nets will make him unable to teleport around and mappa. Whenever he gets stuck in the net, just punish accordingly. I find putting down a net and then a k curse a pretty good defensive setup.
Now, back exe beast, unless you predict he's going to do a far dandy, will almost always whiff. Back exe is really unsafe so to speak. I find forward exe beast the most useful when trying to beat out someone who abuses short dandy into pilebunker.
About Slayer's pokes, try not to punish anything other than a pilebunker & crosswise heel because he would immediately just dandy and pilebunker again for counterhit. Just wait his pressure string out and jump & dash away whenever he teleports.
Thats all I learnt from playing a friend :x If anyone wants to add on, correct or offer a better solution. I'm all ears
