+1/+1 Counters Matter The backup ability is tied to +1/+1 counters, and there are literally more cards that support that theme than you could put in one Commander deck, but I picked some here that stood out to me the most
Animus of Predation Armed // Dangerous Atarka, World Render Cabaretti Initiate Deathleaper, Terror Weapon Disciplined Duelist Domri Rade Drizzt Do'Urden Indominus Rex, Alpha Jetmir, Nexus of Revels Kathril, Aspect Warper Loot, the Pathfinder Majestic Myriarch Marisi's Twinclaws Okoye, Mighty and Adored Picnic Ruiner Rafiq of the Many Rayami, First of the Fallen Roar of the Fifth People Runes of the Deus Samut, Voice of Dissent Samut, the Tested Sangrite Surge Savageborn Hydra Selective Adaptation Toph, Greatest Earthbender Trostani, Three Whispers Veteran Cathar
Yzma, Scary Beyond All Reasons ability makes her worth the cost alone, but she wont go to waste once shes entered the field, either
This is that mid 99 search I did in the introduction