High Evolutionary being a 4-cost has synergies with Zabu. Incidentally, evolved Shocker can function as a secondary way to play a 4-cost on 3. This deck can play a 4-drop on 3 in 62% of games played, compared to Zabu alone managing 45%.
Wasp + America Chavez means Shocker hits meaningful targets more often.
Shocker+Zabu can enable two 4-drops on turn 5.
Scorpion, Wasp and The Thing provides discounts for Abomination.
Moon Girl + Abomination/She-Hulk allows for a lot of stats on turn 6. Alternatively, if we Moon Girl on 3, we can combo them with a 4-drop on 5.
Napkin math: The chance of drawing Zabu in time for turn two is 5/11. On turn two we will have drawn five cards, and America Chavez can't be drawn. Our chance of not drawing a 4-cost in time for turn three is negligible (\<1%). Given that we did not draw Zabu, our chance of Shocker is 5/10. Our chance of Shocker hitting a 4-drop as the leftmost card is 5/8. There are eight remaining possible targets as Wasp is either played out or in deck, Shocker is played out and finally Zabu and America Chavez are still in the deck. This means that our deck will be able to play out a 4-drop on turn three 5/11 + 6/11 * 5/10 * 5/8 = 0,625.