How does this happen in Pokemon FireRed?

Question

I was fighting Tyranitar in Gary's team after the Elite Four, and it used Aerial Ace. If it is a ground/rock type, how did it use a flying move? I just want to understand that.

Answer 1

tyranitar is rock and dark

and for it using aerial ace i have no idea

i guess it can learn it from a tm

Answer 2

Don't ask. In the elite four in Diamond/Pearl, a rapidash knows solar beam.

It doesn't make sense sometimes

Answer 3

Just like my rival on Diamond, his Infernape, fire and fighting type, he knows Aerial Ace as well. My Grotle, Grass type, he knows Iron Tail. My Lopunny, Normal type, she knows Thunderbolt. All these can be learn from TM so teach your Pokemon different type moves, they can be strong too.