It might be neat if players could set what side each enemy is on.  This way they could put them all on the same team, have beach creatures fight wood creatures, have beetles fight spiders, etc. 

If you wanna go all out, players could even set some creatures to their own team. 
And on the sixth day, God created ant in his own image, and gave them dominion over the earth and all of its creatures.  Amen.