Much of this depends on the teacher. Sometimes they have a policy of how they send out information and won't want to change it. However, many of the one's I've interacted with over the years are also strongly in favor of keeping all parents and guardians informed about progress, behavior, activities, and so on.
The simplest solution is electronic communication. An email with information about general class information (field trips, classroom activities, reminders about days off or project due dates) is easy to send to any number of recipients. Our kids' teachers have increasingly come to prefer email instead of paper forms (which are easily lost or damaged in backpacks anyway), although we still get physical copies of permission slips and report cards.
We had one teacher who published her general class newsletter on a (secured) blog. This was great for general information ("Now in math we've started learning multiplication!") but not necessarily urgent updates ("Due to an unavoidable schedule change, tomorrow's class assembly is cancelled").
Both my spouse and I receive those class emails. Even though we can communicate regularly, it's so much easier to just say "did you see Mrs Smith's email" instead of first remembering, then reiterating that email. In cases where co-parent communication is limited, having both parents informed separately and simultaneously is even more beneficial.
Email is even better in student-specific situation. (I've gotten three since Monday about an ongoing behavior/homework issue, an overdue school library book, and asking for a working set of headphones.) In a co-parenting situation, you can then CC both your ex-spouse and the teacher (for example, "I will buy headphones for Son by Thursday" or "I found that book under my couch") so everyone's up to date.