What can we safely dump?

so my Ratticate and Murkrow armies are now useless?

All those mons that I kept at low CP I should now either power up or dump?

I would hold off. Maybe lower CP mons will build up motivation faster.

It has been almost a year using prestiger, hold them off until the rework is completely finished and we can see what we need in our teams ;)

Yeah I would hold off unless u are a hoarder like me. Then u could probably find 50 or so more to dump with today's news. I haven't been below like 880 mons in months. Somebody mentioned earlier in the day an idea about having CP capped gyms for defenders and attackers....too me that seems like such a good idea that they will do it sooner or later. It would make so many more mons be/stay relavant.

Nothing yet...nothing has actually changed yet.

How does 'Motivation' get removed from defenders we defeat?
If the answer is similar to how we used to prestige, then it is possible we will need our prestige army to now efficiently take down a gym...and our high levels mons are for raids from now on.
You may need everything you have still.

I dumped all the Raticates leftover from mass evo and a few lesser Noctowls. Umbreon and Wigglytuff will be defenders or (possibly) fighters that kick out high-CP 'mons the fastest. Somewhere it was mentioned that getting beat by small fry will demotivate big defenders faster, and that totally makes sense as it would hurt a Dragonite's pride to be defeated by a puny Wigglytuff.