I played Nico for about a year straight when M2E first came and had a pretty good track record with him, so i will throw in my 2 cents:
Maniacal Laugh, Undertaker, - I almost always take these together, Mindless zombie is sacrificed when you use it to summon off and undertaker gets you a card for it, so its some inbuilt card cycle, for doing what nico does anyways, and once its a mindless it makes it my corpse marker.
reaper grin/love thy master - sometimes for each but thats the disposable upgrade for me .
Mort with corpse Bloat and sometimes my favourite shovel - fresh meat used against one of my own crooligans or necropunks, will have most of my crew at centre table first turn 1 if i want. otherwise i can walk and still find a bone because of the extra AP. expensive but useful. Fresh meat is absolutely amazing. potentially giving every undead 3 extra walk actions a turn is damn near broken.
Toshiro the Daimyo - he is my front liner with all the summons as he gives the + flips to minion ML attacks and i dont have to extend Nico a lot. i will give him command the graves if some declares Arcanists so i can potentially steal their scrap markers. he also gives out fast which is excellent on punk zombies.
thats kind of the core I like other things that get thrown in a lot are Phillip and the nanny w/ take back the night, in scheme marker heavy games i will summon drowned pretty frequently so this works well.
sebastian with those are not ours sometimes as he can lurk at the back and generate soulstones for me
nurses are always great.
i will have a necropunk or a crooligan as well that can get up the table fast or in a good position to be a target for fresh meat for Morti, which will get almost everyone up the table.
typically i will summon a rotten belle and 1-2 scheme runners on the first turn, once they all get pulled forward by the fresh meat to where i want to be set up, the belle will lure nico forward, so i dont have to waste his AP walking. then its just summoning whatever works but it is typically, drowned for fighting and annoyance in the middle, hanged if i have the cards, and for the no immunity aura thing. you will out last him and your getting cards whenever he kills things within 6. you should be out activating him very quickly as well so it becomes very easy to control the board.