A LOT of batteries...
Non-electrical people often have no way to conceptualize what it means to say "125A for a few hours". Just to give you an idea, a Liebert 30kVA UPS with internal batteries is maybe 15 minutes of hold-up time. To get 2 hours, you would likely need their largest external battery rack. The UPS with the internal batteries is 24W x 40D x 79H and weighs 678 lbs, an external battery unit that MIGHT be capable of 2 hours of backup is another cabinet, 35W x 40D x 79H and another 1678 lbs! So you are looking at well over a ton of equipment here...
And as noted, this is 3 phase only.
Oh, and you are looking at somewhere in the neighborhood of $50,000