I'm willing to completely change many of these effects. I just came up with the first ones I could think of. The power levels are all up for debate as well.
Memory Flood is especially good after a Compulsive Research, but dead until turn three in most decks. I still can see it being too strong. It could alternately have a Memory Lapse or Remand type effect: "Counter target spell unless its controller pays

. If that spell is countered this way, put it on top of its owner's library."
The black one could stay creature removal or become discard.
Ancient Trees is stronger than Harvest Wurm, I think, but just as hard to play. It comboes well with Rogue Elephant, but is nearly useless without other discard outlets. Maybe it would be good in madness, but then it's on par with Basking Rootwalla.
I changed Trench Defenses to a mini-Ghostly Prison effect, which is much more interesting.
The red one can change to any number of things. I think it would be broken if it could hit players. On second thought, I'm so tired of red getting damage spells in these cycles. Is there anything better than artifact removal that this could be? I'd use LD but then Raze and Crack the Earth break the card badly.
All of these combo well with other ACC cards, but don't do much on their own. Still, it's a hard drawback to balance because it can actually benefit you once you meet the requirements.
If you would like to see white get the proactive card in a cycle, see my last cycle:
Barkhide Armor, where white gets the creature instead of green. Incidentally, these cycles have enormous synergy.