Pretty much any bait in a pond that is catching fish is a start. As has been said upsizing usually helps eliminate some dinks but ponds are more what the fish is in the mood for. The confined space of ponds means its equal opportunity eating. Large fish just as much as small fish see the baits its just a matter of does the bigger fish want that. At least that is my theory So imho your still going to get small fish even large baits catch small fish. 

Me personally I would try a 10" or 12" worm on the bottom. Or a nice size 1/2 oz jig with some 4 or 5" meaty trailer like a Pit Boss.  

I fish a farm pond regularly as well and find them holding tight to either the bank or other structure. Senkos, chatterbaits, spinnerbaits, jigs, worms and topwater have all worked for me well. I have caught 1lb fish on a 10"  worm and a near 7lb bass on a minnow with a transformers kids rod in that pond. That fish was nearly as long as the rod !! There is no real guarantee on any lure of results for size.