From the looks of that last screenshot, whatever Halos you add into the pot gets a multiplier added onto it so the potential gains are massively larger than the actual losses instead of the typical "double or nothing" which means that there's a pretty good incentive to hop into co-op every so often for that brief boost you need for that next upgrade. I'm still not clear whether or not the players are betting against each other or if it's a shared reward based on whether or not you both are able to complete the Verse (which may be possible, since both characters look like they have only base health and magic to work with).
Also, looking at the top right of the screen shows a tarot card similar to the ones that represent the Verses with a counter showing "9/52" on it. I guess this means that co-op players will have a pretty good choice of which fights they'd like to partake in. Though 52 Verses seems like a pretty shallow number compared to the first Bayonetta, so it's likely not indicative of the number of Verses in the final game. Hopefully they cherry-picked the best Verses to put into co-op.
Hopefully these little revelations means we can learn a bit more about the multiplayer during Comic Con, Gamescom or TGS.
