A question came up during a game tonight: I activated a Nexu and used Beast Tamer to give the Nexu 6 MPs. I then played Pummel. Can I move between the attacks of Pummel?

No. Pummel is a single action that costs ╔►╔►. You must resolve the action fully unless you have another ability that states it interrupts.

You could spend 2 MP, Pummel (attack twice), then spend 4 MP. But you cannot Beast Tamer, Pummel, attack once, move, attack again, move more.

"Actions", RRG, Page 3:

Movement points can be spent before or after performing an action. If movement points are gained as part of a special action, they must be spent immediately during that action.

Cool, thanks!