I'm new to this forum so sorry if this is in the wrong section, however, I have been playing commander for a couple years now and I was browsing the new ravnica allegiance card spoilers and saw this mechanic. 4GU: Adapt 4. (if this creature has no +1/+1 counters on it, put four +1/+1 counters on it.)
Sultai are great color for a graveyard commander deck, Sidisi, Brood Tyrant, Muldrotha, the Gravetide and The Mimeoplasm all make awesome graveyard deck commanders. Including Zegana, Sage and boosts to +1/+1 counters suggest a heavy thematic focus on +1/+1 counters, so if you want to be doing that, maybe Atraxa, Praetors' Voice would be the go-to commander. If you go all-out on the +1/+1 cou nter theme, there are lots of cards and very nice combos and synergies. If you rather want to focus on your graveyard theme, I would recommend to go for overall synergies there instead of specific combo pieces that have little functionality on their own. E.g. Necrotic Ooze works super well with other graveyard goodies such as Havengul Lich, Whisper, Blood Liturgist and Avatar of Woe...
You will probably get better results when focussing on one theme OR the other, but commander is a format all about doing whats fun for you, so if you want that +1/+1 counter graveyard combo deck - you do you!
By the way, this forum is for discussing the rules of commander - like the banlist, commander-specific rules, etc. Card Ruling have their own forum, and this thread about building a commander-specific combo could be in the general forum.
Card advantage is not the same thing as card draw. Something for 2B cannot be strictly worse than something for BBB or 3BB. If you're taking out Swords to Plowshares for Plummet, you're a fool. Stop doing these things!