Bair is awesome. When combined with Charizard's three jumps, it's completely possible to hit an enemy with multiple hits. It comes out fast, and if it sweetspots, it's got pretty solid knockback. If it doesn't and you read their DI right, go for another one. It's great for pressure.
You have to be careful with fair since if you don't sweetspot it, the enemy will just punish you once you hit the ground. Fair is best when edgeguarding since you can't be punished as easily when you're offstage, in most cases, of course. That said, it's still a move you should use onstage, too--just get used to how it hits. A lot of times people use fair and DI backwards so that if they miss the sweetspot, Charizard will be farther away from the enemy, making it harder to punish.