Powerful Bluetooth portable speaker for outdoor use (Rosemount AB25)

Hi all, I'll soon start out running Zumba classes and taster sessions, including some outdoors, and I'm looking for a decent Bluetooth speaker to see me through the early days.
It needs to be loud enough to carry over background noise for a group of 10-20 people outdoors, so ideally something like a JBL Charge, Flip, PartyBox, Boombox or similar rather than a small personal speaker. It's for my professional Zumba sessions, so it does need to be in good working order (battery holds charge, no distortion at volume).
Happy to collect anywhere in Aberdeen, ideally within walking distance to city centre. Thanks so much!