I'm not a DeGrey player, but here are some notes on various moves:
Counter-Point Step followups all have very important properties. First off, the A followup is +10 on block. This is crazy. It's definitely not your opponent's turn to push buttons here.
Second off, the B followup, Pilebunker, has two important traits: It's throw invulnerable, and it also breaks armor. (This means it's very good against Rook, since he can't C throw through it.)
The C followup is, as the move list says, invincible. It beats a LOT of things, but not everything. For example, Geiger can react to it with a Flash Gear. You can use it to go through projectiles depending on spacing and timing, but this is tricky business. It's easy to come up short, or get blocked, etc. if you do it slightly wrong.
If you let them block the B or C followup, expect to take at LEAST two damage. Also, you can be tricky by doing empty Counter-Point Step and then throwing.
Ok so let's talk about Pilebunker combos for a second. Obviously, there's the iconic counter hit Pilebunker -> Pilebunker combo. (Does not work in the corner.) On regular hit in the corner, you can follow with neutral A, but do NOT do the second hit of neutral A, because that will whiff.
DeGrey's ground super doesn't work on projectiles. He has various answers to projectiles, but this isn't one.
DeGrey's air super does 3 damage on counter hit. As far as I know, this is ONLY when you hit your opponent's startup; it's very hard to use this as a reaction for 3 damage. You'll probably have to predict.
Air B -> B is unsafe. I believe you can make the first hit safe if you space/time it right, but the second hit is, as far as I know, always unsafe. Also, obviously, air B massively changes your momentum; this is really important for avoiding projectiles etc.
Neutral A -> A is +3 on block, and neutral A on its own is a massive +5(!). This means it's not really your opponent's turn to push buttons.
Forward A is throw invulnerable. Its tall arc also means it's good at hitting people in the air. If you get an air hit, you can follow with Pilebunker. Forward A is also +1 on block, so your main fear is being interrupted.
Ghost eats other projectiles; it just goes straight through them and keeps going. This is a MASSIVE boon against projectile characters like Grave, Geiger etc. When you have ghost off cooldown, they should be afraid to throw their projectiles. If you threw ghost first, ghost should catch them, but even if you threw second you can probably make them block.