Greninja was the hardest to deal with of those characters.
I think you have the right Ile customs, but projectile Aether > diagonal Aether, IMO. The stun counter is vile.
Up Smash has almost no recovery. It is good to throw out as a bait, though sometimes you beat my bait. -_-
Fsmash pulls his hitbox back, so it is a great counterpoke. Some Dorf players claim it is also upper body invincible. It beats a lot of aerials.
The custom down B beats projectiles on reaction, which is the primary reason I have it. It shuts down ZSS' ranged game, Link's ranged game, and a lot of others.
This is my first day using his standard side B. Otherwise I have been using custom 3. I am not great at follow-ups with it. I know some good setups, I just haven't practiced them yet. Using utilt as a ledge guard was new for me today. Shout outs to the utilt and Warlock Punch kills.
Could I have avoided your ZSS and Greninja throw combos?
Total opposite.