2 letters:
bt

4 letters:
bats, batz, beat, beet, bets, betz, bits, bitz, botz, buts, butz, eats

5 letters:
baatz, baits, bates, batts, bautz, beaty, beefs, beeks, beeps, bertz, bet's, betts, bites, boats, boots, bootz, botts, bouts, burts, but's, butts, bytes, deats, deets, deetz, deitz, dietz, feats, gaetz, heats, keats, keitz, leitz, lietz, meats, meets, meitz, neitz, paetz, peets, peetz, peitz, pietz, raetz, reetz, rietz, seats, teats, teets, tietz, viets, weitz, zeitz, zietz, baetz, beats, beitz, bietz

6 letters:
bates', beasts, beater, beatie, beatty, boat's, cheats, heat's, keatts, peat's, peet's, pete's, seat's, sheats, sheets, sheetz, yeatts

7 letters:
beattie, scheets, scheetz