Translation:My dad is watching a basketball match.
It's "basketball game", not "basketball match".
"basketball game" works. I guess it's more idiomatic, true, but at least "match" directly translates to "mecz".
'Contest' is another possibility; but 'game' is clearly the most idiomatic.
I fail to see how "contest" can be used for a regular Sunday NBA game.
Why? Are they all expected to be blow-outs?
Well, anyway if you use it, it translates to "konkurs" or "zawody".
Tennis match, basketball game. Volleyball match, basketball game.
Co o Koszykówka gra?
Sorry, but I'm grammatically confused... what did you mean?