Hate to break this to ya - i've been specializing in Necalli since before launch, and have come to the decision that Necalli is, by far, the worst character in the game.
As to your question, his only 'real' combo that starts off lights would a counter hit cr.lp->cr.mk->bf lp charge.
Now, into detail why Necalli is the worst character in the game. Let's talk about his Crush Counter buttons for a moment. Two of them, Cr. HP & st.Hp, will ALWAYS knock the opponent into an aerial spin on hit, and the only thing Necalli can follow this up with is either super, a stomp, or st.hk. Most other characters can get actual combos & even get some wake up setups off of a crush counter. Necalli? Stomp, if you weren't that far out.
What about st.hk? Thats a crush counter right? Yeah, sure. Its a great normal for Necalli. The problem is both in how far back it pushes the opponent out, and its start-up time is so long, it will get stuft if you try to throw it in near-close/medium-close range footsies. Optimally, you'll be in a medium-close range when you land it, allowing you to walk up st.hp into his bnb (st.hp->mk stomp->cr.mp->bf.lp charge) but thats only really going to work if you were at the appropriate range. See, most of Necalli's normals push your opponent out a tremendous amount.
Most characters get to throw out 3-4 cr.lp or cr.lk block strings, starting from near-close range, to push an opponent out of close range. Necalli gets 2, if that. None of Necalli's lights are fast enough to actual beat a spamming lp or lk on block, so if you even think about hitting a button, you just gave your opponent a free counter. Necalli even has a cr.mk that has some of the longest startup for what is ideally meant to be a fast & long range poke that doesn't really lead into anything, which it doesn't for Necalli.
See, Necalli doesn't actually get a whole lot off of his footsies. He doesn't get good positioning. He doesn't get good setups. He gets 'some' good damage, depending on two things: 1. did you counter hit on his cr.mp/st.mp/cr.mk? 2. Do you have a fast enough reaction to switch your lk.stomp to mk.stomp? At higher levels of play, stomp is super unsafe. Its intimidating for new players or lower ranks, especially because of how much block stun you have to eat, but unless you know it, its actually super unsafe in its mk/hk iterations. The only reason you'd wanna use the lk version is because it is guaranteed to combo off of cr.mp/cr.mk without needing a counter hit, but you don't get to follow-up after it hits, plus it has way fewer frames of recovery, meaning you might just eat a jab or lk instead of a mp or mk instead.
So, two of Necalli's better footsies, st.hp/cr.hp, are basically nerfed by ensuring you cannot get a full combo off a counter hit. If you're a Necalli player, and try using that button, you'll see that when you use st.hp/cr.hp, it actually lands a lot. Its a solid button. Good luck turning it into anything meaningful though, unlike the rest of the cast and their hp buttons.
But Necalli has a dive kick! He's the only character in the game with a dive kick that isn't a special! Yeah, that dive-kick is ass. So, it not only stalls you in the air, which, depending on your opponent, is giving them even more time to anti-air you, BUT, you don't even get anything off of it. Even on counter hit! The most you can get from a down.HK aerial dive kick is 2 jabs into ex. stomps. Compare that to any of his other jump ins, even jumping mk, which gives him st.mk, or either of his other jumping heavies, which give him st.hp, and you can see why you'd never wanna use the dive kick for a jump in.
What about Super Saiyan Necalli? The best thing about v-trigger Necalli is that you can now combo cr.mp->mk.stomp on a clean hit (normally, this has to be a counter hit). This, in conjunction with the huge buff Necalli gets to his dash distance & speed, makes his v-trigger form actually quite scary to deal with. You dash in & either command grab or cr.mp->mk.stomp (you can even do two rotations of that before you push your opponent out in v-trgger) to keep up his pressure. Necalli's already useless v-skill even gets a buff on his recovery frames during trigger. I mean, its still 'mostly' useless, you just might not get as punished for daring to use it.
Honestly, as a Necalli player, I would GLADLY eat a 15-20% flat damage nerf across the board if it meant removing the design handcuffs that are currently plaguing the character. Necalli & his kit actually have a lot in common with Bison (both characters specials & normals are very frame-trapy). However, Bison outclasses Necalli in every imaginable way. If you're a Necalli player, I highly recommend looking into the boss of Shadowloo. Not only do you get a character that has frame traps, but none of the kit handcuffs, AND you still get to retain the insane damage Necalli dishes out.
