Many of the early bannings were cards that either produced fast mana (like Tolarian Academy or Lotus Petal) or were broken because of fast mana (like Windfall, Memory Jar, and Time Spiral)
While blue is the king of counterspells, the other colors have a few options they can use
Cards can be found in story duels, challenge duels, and character booster packs and, frankly, they aren't hard to get
What are you using Green for
Angelo Cannon - Whenever Rinoa Heartilly attacks, another target creature you control gets +1/+1 until end of turn for each creature you control
Lower Text - Promo Info 1st year Anniversary adventure pack CLOSECLOSE BT1-088 R Tamer Parallel Rare Koshiro Izumi Color Green Form - Attribute - Type - DP - Cost 2 Digivolve Cost 1 - Digivolve Cost 2 - Upper Text [Main] If you have a level 5 or higher green Digimon in play, you can suspend this Tamer to reveal the top card of your deck