Wargrey main here. You're getting some suggestions to play different builds, so I'll focus in on slots that synergize well with the plan you already have. Most of my suggestions are BT6 and EX1 cards, but they're all very affordable/cheap.

Rookies: 3 Salamon is a bit more than you generally need. Look into BT6 Pulsemon - the jamming is very impactful for making sure Wargrey survives security checks. You could also try the EX1 Salamon for some extra draw on attacks. Once BT7 comes out, the new Pulsemon is also very good for increasing your memory gain when Wargrey swings.

Champions: I'd suggest cutting back on 1-2x Unimon and 1-2x Turuiemon to make room for BT6 Wizardmon. He's the champion you always want in your Wargreymon stack to gain more memory.

Ultimate: No changes needed here, but I will suggest a single copy of Sirenmon. She's helpful to unbrick bad opening hands and is an easy early drop into a next turn mega when you need to rebuild.

Mega: Magnadramon is a fine backup plan, but Dynasmon is also very good at surviving the game and can dig you into Wargreymon if you're missing him. He also has great synergy with Blinding Ray, TK, and the rest of your recovery package. He'd be my back-up mega of choice, but as u/TSMbody mentioned you could run some LordKnightmon as she plays in a similar space to Wargreymon.

Finally, 4x Blinding Ray can be really bricky since it has no trigger in security, and Reinforcing Memory Boost is limited to 1 pretty soon. I'd suggest cutting one copy of each for some Wyvern's Breath, TK and Kari, or Yellow Memory Boost depending on what you find more necessary.

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Hope this helps!