Should i power up Ho-oh

MetagrossMaxis,

The best counters for the solar beam Groudon are Flying dragons and grass. The dragons double resist solar beam, and dish out great neutral damage. If you have Rayquaza, Dragonite, or Salamance with double dragon moves, you're set (Hydro Pump Salamance is also an option, and don't worry about Groudon having Dragon Tail - it hurts some, but not enough to make dragons unusable). Alolan Exeggutor (also dragon) is also good, with it's double resistance to grass, and it counters with Bullet Seed/Solar Beam, which Groudon is weak to. Exeggutor also does well, albeit not as well as Alolan, and Frenzy plant Venusaur does fine work too. Further, all of these options except Rayquaza don't require Rare Candy, making it much easier to power them up to higher levels.

Kyogre still wins out in DPS, but won't be around long. You might consider leading the team with your strongest Kyogre, get off one hydropump, and then let it fall and bring in the grass and dragons to do the heavy lifting (that's exactly what I'm going to do). As long as you have enough revives, this works pretty well. A Kyogre in any spot but the first runs a much greater risk of not getting a HP off.

So, as the above posters pointed out, Ho-Oh is an option, but a low DPS option. Of course, if there's 18 people at the raid, winning it is a foregone conclusion (unless they are almost all noobs), so you might use something like Ho-Oh to curb your potion expenditures. But you'll also be sacrificing a damage ball to do that. Is that enough to justify the investment of substantial rare candy? I'd argue not.

The only Ho-Oh I powered up to level 31 (breakpoint) had Extrasensory/Brave Bird, and I use it as an anchor for Machamp solos, because I missed out on Lugia (and Ho-Oh single resists everything Machamp throws out, instead of double against fight and nothing against steel). I still use it in that role, but all my candy from Ho-Oh's return is sitting around unused. (I've got a few Lugia now, but not interested in powering one up, since Ho-Oh is doing the job just fine, and has better attack than Lugia, with poorer moves.)