I was dueling my friend with yugioh cards and i think hes cheating...?

Your friend is wrong. When he summons shura the blue flame, you activate bottomless, starting a chain. When the chain resolves, the monster is destroyed, and there is no blackwing monster on the field to special summon bora. The funny thing is, even if your friend was right, if they were both special summoned at the same time, your bottomless would remove both. If you read the effect, it destroys any special summoned monster(s). So both would be gone...IF your friend was right.