Both countries have strong teams in some sports - Australia the "commonwealth" sports of cricket and rugby (both codes), Germany most obviously football - but there doesn't seem to be any overlap.
Is there any team sport in which they are arch-rivals?
Mens Hockey. Australia are world ranked 1 and Germany are ranked 3 (England are ranked 5th). In Womens Hockey, Australia are 2nd and Germany 5th in the rankings.
Mens Hockey. Australia are world ranked 1 and Germany are ranked 3 (England are ranked 5th). In Womens Hockey, Australia are 2nd and Germany 5th in the rankings.