Is Golem already useless??
As a Ground attacker was never that good but now it had been left far behind by Groudon. As a Rock attacker is still the best but... for what? The bird Legendaries are gone and some more impressive monsters are coming so, is that it for good ole Golem?
Does it gets any other evolution?
Will be also outclassed by some new Legendary or Gen3-4 pokemon?
Answers
I don't know about future evolutions or replacements who will surpass Golem but I know we will see quiet a lot of Golem if Rayquaza will become a raid boss. Most Dragons habe a dual flying typing and most of us don't have 6 Ice-attackers, the biggest weakness. Articuno and Lapras are “rare“ or need rare candy imvestmnt and after that all ice attackers have flaws. Then Rayquaza is weak to fairy, dragon and rock. There is still no double fairy mon even though Gardevoir will enter the szene. Dragons are weak to Dragon, so this is not ideal even for Dragonite. So I would say that Golem will have a huge use in this matchup again.
I will go with Dragonite, Lapras, Cloyster, Golem, Golem, Dragonite and will porobably not make the investment for Articuno but maybe switch one Dragon for a Pilowswine.
The attacker of choice for dragons will be Kyogre with Dragon Tail and Blizzard, and no one else will be close. Even without STAB, DT/B Kyogre will shred the flying dragons like nothing else.
This leads me to an interesting prediction. We probably got Groudon before Kyogre because WF/HP Kyogre would shred Groudon. Since DT/B Kyogre will shred dragons, we might see Rayquaza and/or Salamence before we get Kyogre.
If Rayquaza became new t5 tomorrow than could be, but after few more weeks probably everyone will have good ice team.
Walrein available and Spheals are very common right now, at least for me.
Laprases are also common during this event.
With proper weather you could catch wild lvl35 spheal/shellder/swinub/lapras and get powerful ice attacker which is much better than Golem.
Even if you completely lack water/ice types dragonite do this job much better
I'm not sure about the dragonite point but it is close probably and depends on rayquazas moveset. As for the ice-types...spheal is really common here too and I have caught around 200, but there is not a single one with a high level and good IVs. You are right though that with time passing, most people will be able to string together a pretty good ice-only team.
Looking at Rayquaza counters on pokebattler, Golem is decent, appearing in top 15 against all movesets. Ice-types and Dragonite are much better DPS-wise, but for someone lacking a full team of those, Golem has use.
Note on Gardevoir, it has better DPS against dragon/flying than Golem but bit less TDO. Also a solid choice if lacking ice-types and the boss has even one dragon move. Both are better than DT/O Gary.
Golem should still be the best rock type attacker in Gen 3 assuming no moves are changed.
Regirock does have Rock Throw + Stone Edge as an available moveset but it's attack is lower than Golem's. It's defence is higher, giving it about 50% more bulk but it's like comparing Machamp to Hariyama.
One lasts longer and does more total damage before fainting, the other deals higher DPS, and currently DPS is what counts, because you want more damage bonus especially when raids don't always go down to the wire that 6 Golems could survive the raid anyway.
Gen 4 only has 2 new Pokemon that learn Rock Throw - Bonsly and Probopass - and both are useless.
Plus Gen 4 is ages away, we've only just got Gen 3. Even if it were the case that Gen 4 releases a Pokemon that outdoes Golem, if there's currently a boss that Golem is really strong against, that makes it still worth powering.
Golem isn't the top counter to any of the Gen 3 legendaries but maybe we could see the Gen 1 legendaries returning in the future. They already were re-released in some safari event.
I didn't read all the answers you already got, but Rock Throw/Stone Edge Golem should be one of your best counters against Rayquaza - if you have not already built a powered up army of strong Ice Pokémon (like Articuno and Lapras). Assuming you have already powered Golem up. I only have 3-4 powered up strong Ice Pokémon, so I will definitely also use my very strong Golem army against Rayquaza.
