if you towing the trailer without a battery, you're probably breaking the law, at least in the U.S.
since the the trailer has electric brakes and a emergency breakaway switch, you need a battery hooked up in case the trailer separates from the tow vehicle, to activate the trailer's brakes.
if you always have electric(hydro)hookups, any cheap deep cycle 12v group 24 battery will do.
if you plan on doing some dry camping or boondocking, then you need to look at a two battery setup, either 12v or 6v deep cycle. either choice should have matching batteries.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC