Like just general advice? Whiff punish with st.MK is really good. And on hit you can confirm into cr.MP LP disc or v trigger activation.
Since you watched the bafael video you probably already know his punish combos and stuff.
Anti air with jab and dash in/walk forward after the air reset for a mixup opportunity otherwise you anti air with his HP DP.
Necalli's normals are kinda stubby but v skill does give you a fullscreen option so use it when you need to.
You don't really want to get predictable with canceling into stomp with blockstrings because other than HK which is 0 they are all negative on block. Just go for frametraps and throw/command grab mixups instead of always canceling into stomp in blockstrings.
His overhead is really good and builds a bar of v meter on crush counter.
Generally you want to activate v trigger as soon as you can for the advantages it gives you, but be mindful that it means you won't be able to v reversal for the rest of the round. Activating off of certain normals leads to frame advantage as well, like cr.MK on block xx v trigger activation is +, so you get a mixup opportunity after it.
The type of meaty you'd want to use varies on the different knockdowns he gets. But one thing I see necallis do online alot is just a manually timed st.HK meaty. st.HK is -4 on block if it isn't done meaty enough so that's kinda risky without a real setup, I wouldn't do that. I dont main necalli so I don't really know all of his meaty setups, but check out this guys videos if you want to learn some
https://www.youtube.com/user/Bri4nF/videos
If you have any speciflc questions feel free to ask. I had a weird some issues when starting out with him because I felt like his optimal range in alot of matchups was a way closer range than what i'm used to lol. But he's a pretty fun character, lots of options.