Scyther Solo

The best choice is RT/SE Golem powered up to about level 30. After that would be Tyranitar with SE. After that, if you have solid a solid flareon out jolteon at close to level 30, they can succeed. Other solid choices would be your raikou and entei as is, but their lower level may hold them back.

Try looking for golem raids. He will also be ideal for Ho-Oh.

What levels are those pokemon currently?
Dragonite is probably worth powering up in any case. The only reason not to would probably be that you have a Dratini with better IVs waiting for evolution.

For Flareon and Jolteon, you should try to catch high level Eevees rather than power up, unless you have great IVs. Flareon is better out of the two of them.

Ampharos isn't a good attacker, don't power it up for that.

With a team of L30 Hurricane Dragonite, L30 eeveelutions and the Zapdos or Entei in last spot you should easily be able to do the raid.

Also, if you can catch a high level Sudowoodo in the wild with rock moves, that would be a solid addition to the lineup at no stardust cost.

I have two RT/SE golem and a TS/WC Raikou that between the three of them can almost finish off a Scyther Boss. I usually clean up with one other decent fire type like Arcanine, Ninetails or Entei. By far and away it's the 2 golems that make this boss easy for me.

I'd go with double fire Arcanine or Houndoom over the electrics. SE Tyranitar would be a decent fill-in also.
Check out this site for info about breakpoint optimization.
https://dominikzen.com/pgo/attack-pro/

Second (or third, not counting) the rec for Golem. I have a trio, all RT/SE, levels 35, 33, and 33. They fight the Scyther, and by the time the third one goes down, just past halfway on the clock, Scyther is in the red. After that, I finish with Ttar for Night Slash, Entei for X-Scizzors or Aerial Ace (I'd use Raikou for Aerial Ace if I had one). Easy solo at level 35, should be very manageable at level 30, albeit a little tighter.

Other thing to note is that if you're against Fury Cutter, that does next to no damage, and attacks once every 2 seconds (gym defense AI) instead of every 0.4 sec (regular). Air Slash is much tougher to fight than Fury Cutter - factor that into your post mortems.

I understood that you have at least one Golem with MS and a Rock charge move. I suggest Fast TM'ing your Golem(s). Even one double Rock Golem at a decent level would allow you to solo Scyther reliably.

I'd say that after you have a double rock Golem and that Dragonite at level 30 you're good to go (I'm really jealous for that Hurricane by the way ;p ). Try to get to a Scyther raid early so you can get multiple attempts if needed. You can also power up your Pokémon between tries.

I can do solo Scythers comfortably, my best workhorses being Golem (RT/RB), Dragonite (DT/O) and Arcanine (FF/FB) all at level 30. On top of that I use a level 27 Zapdos and a level 29 Flareon. If I ever get to the 6th I think it could be anything and I'd be just fine.

Best of luck to you and let us know when you go for it! Even in worst case you lose just one raid pass. Finally I'll say this again: get a double rock Golem and you should succeed easily! :)

The guide lists the counters in descending order of effectiveness and also lists recommended minimum levels.

I’m level 35 with mainly level 30 counters and have never lost to a Scyther, but it’s not that super easy you might think with level 30 pokemons. All advice above seem good and rock Golems should be the backbone of your team.