While most would say never to use any rare candies on non-legendaries, I drop some on Blissey/Chansey and Snorlax anyway.
For me now, my “metagame” is gold gym badges. I’m not as interested in the raid meta anymore. I still solo T3s for the challenge, sometimes with 6 unique mons and all that, but I just somehow enjoy the repetitive Machamp vs Blissey battling in GRB-defended gyms. The gym meta is really just Machamps, maybe Lugia, defenders, potions and berries.
I personally think that the lack of an “endgame” in PoGo is good. It means players can choose to play however they want to play, like the raid meta, gym meta, maxing favourite mons, or just collecting different special mons.
Yes, the gym meta is a grind, and might be completely stale in some areas; but there’s some depth to it, at least in my area. For example, getting gold badges is completely different in Instinct-dominant (yes they exist here), team-balanced, Instinct minority, and areas where Instinct stands next to no chance.
I’ve also started a personal challenge to max my Snorlax from L38 to L40 (54 candies) using only candies from feeding in gyms. Yes, I know it’s gonna take about 5000 berries. But that’s also enough gym badge points to take 2 gym badges from silver to gold.
Or wild Snorlax, if I’m lucky enough to see another one.
PS: My buddy now is Togetic, to prepare to max a Togekiss as soon as it drops in Gen 4.
Edit: As for T5 raids here, if you arrive before the egg hatches, it rarely matters whether you use optimal counters or even just slack off in the lobby.
But it does makes a difference sometimes. 2 weeks ago, I was at a L5 Regirock raid right before it started. There were only 5 people (all spread out, no communication) and 8 players in the lobby. The raid finished with 40 seconds left. If I wasn’t there or if I didn’t use Machamps and Kyogres, the raid would have likely failed. While L5 raids in residential areas usually have at least 1 full lobby at the start, I’ve seen (on rare occasions) a few go completely “bo lang” (not a single soul around) for the entire 45 minutes.