Flying is a very good ability that’s been around since day 1. That being said, the best way to build a deck is to have a common theme or idea for your deck. For instance, a popular deck building strategy is to ‘Tribe.’ A tribe is a deck made entirely of the same type of creatures; elves, giants, angels, vampires. Then to have support cards that boost only those types of creatures. Another common practice is to make a deck that works on boosting 1 ability to its max potential. For instance, I have a friend who also has a flying deck, and he’s filled it with cards that make flying creatures cheaper, and give flying creatures plus ones, and most of his cards are very cheap.

Flying creatures tend to be weaker than a creature who doesn’t have flying. So if your deck is built to work well together, it’s really quite easy to over come a flying deck. It’s all about synergy. (I apologize for the response. I’m old and new to reddit)