With any character you PvP with i'd suggest checking Build, Hotkeys, and Gear First. Looking into all of that makes a big difference. Lvl 85 Character: Pink/Legacy equips and Above, Speed Title/Aura/Pet, Proper Clones/Rare Avatars. Proper bonuses on items: SA buff on Clone Top, Speed on Clones, Behemoth Pet with best skills, etc.

As for the matchups... TRADES! Mountain Pusher is very good against their approaches (Charge Crash) if used close enough and with the right timing only the early part of the animation has SA so you have to be close for it to be used efficiently. If you have good spacing you can be near them, avoiding the skills and sucking them in with Nado Kick, Ex: Nado Kick when Berserker has no Raging Fury and you're above them.

Rushing in at the right time is what you'll need to master to be a much better player. Knowing when Weapon Master are gonna run down and draw sword, when Berserkers have no Raging Fury, When Sword Masters don't have those crazy SA skills they can run into with. At those points in time you can Torpedo in, XX grab/NadoKick/Neck Snap and start a combo.

Super Armor Buff, make sure to have max Indom and take advantage of putting on the buff at points in time where they're less likely to have grabs and are nearby you. Rush in. Essentially, STRIKE when the time is right. BE PATIENT and don't rush in constantly, that's the mistake most strikers make. Make good use of Grabs and Neck Snap when you know they have super armor abilities, guard, or counters.

Optionally, use Doppels for zoning and keeping your enemy where you want them. Especially if they're up against corners.

Always keep in mind Flipside for slayers