What new defenders do you expect will be viable?

Basically every pokemon which has high stamina/def and a quick move dealing lots of damage, e.g. slowbro with confusion

Hypno, Tentacruel, Wiggly, Venusaur, Miltank and my beloved B-IP Poliwrath will be some of the defenders I'll love to put in gyms. Maybe even Chuckles and Wobuffet.

It should greatly help pokemon that don't have double weaknesses. The Nidos should make a comback. Maybe even some stuff like Weezing...

i have my slowbro and my 2 laprases with double ice who went into retirement from gyms some months back. Ive also a 97% iv wiggly who im gonna try out.

I think Muk might be reasonable also

This is difficult to predict, since we don't know how motivation will work - ie, whether the "stronger" criteria that makes some pokemons lose motivation faster is based on raw CP, or the species (or species max CP? Or species tier? They already sorted species into tiers for raid bosses). It's quite possible that there's a new trait for pokemon that determines how fast that species loses motivation - and if there is, that will be a very important factor.

Hell, we don't even know if motivation is additive or multiplicative, or whether some species will need more berries to restore motivation than others. There could well be 2-3 new numbers for each species that need to be weighed here.

I also want to try out Wheezing.

I'll be investing in and using my IS/IB and IS/B Lapras', my B/IP and RS/IP Poliwraths, my C/IB Slowbro, and my DT/HS Steelix.

I may use a few more like Umbreon, Tentacruel, Hypno, and Muk once we know more.

Tada!!!!! The New Meta! And of course a few more.

I can see Donphan benefitting from this. No double weakness, and his decent moves (e.g., Counter, Play Rough) won't be so nerfed by lack of STAB anymore. Full disclosure: I have a 98% C/PR Donphan at level 36.5 that I'm just dying to put in a new gym :)

What about starmie with bug hidden power/psychic? Too gimmicky? Even possible? Might trick a couple people on the first pass...

I wonder how Lickitung would perform. Seems to have quite a lot of HP and decent DEF, just not really high on the attack side.

Just blew all candy on my oldest, IS/IB Lapras, gonna be queen of gyms.
Not doubting about Slow-folk and Poliwrath, but I wonder if Bubble/Blizzard Politoed is worth the dust if it's just under 1k CP (evolved to be a fancy prestiger). I bet ppl would love to see it in gyms, it has a fun attack animation.

My 100iv ampharos with VS/ZC might be good now?

Wondering whether high defense stat Pokémons will be more useful now, perhaps in terms of motivation/berries.