My all time favourite sports game was Dorakey No Kusaykiu on SNES. It's a Japanese baseball game in which different animals play against each other, sponsored by a variety of well known US and Japanese drink companies. Brilliant to look at, brilliant to play (even in Japanese it's easy to work out the controls). And considering I'm someone who absolutely loathes sports games, that's saying something.
There have been many nights in my household staying up late playing this. Sheer brilliance.