Predicting Legacy Moveset Value

TL;DR version: So far the GameBoy games have been a pretty good predictor of move-set value.

I came to another thread late in the discussion and I think it got buried too quickly so I just want restate it here. I'm sure some of you may have already noticed this but just in case you haven't, it may be helpful for the hoarders out there who are scared to transfer mons with legacy movesets.

For those of you who played the original games, you are probably familiar with many of the moves. And it seems that PoGo has tried (so far, anyway) to keep the moves performing similarly to how they do in the GB games.

Consider Dragonite:
https://pokemondb.net/pokedex/dragonite#dex-moves
As far as Dragon moves go, Twister has always been pretty terrible (only 40 power), and Dragon Claw (80 power) is way better.
As another example look at Dragon Pulse (85 power) and see that Outrage (120 power) is strictly better (ignoring Category and the confusion effect, anyway).

Looking here:
https://pokemondb.net/move/all
and filtering by Dragon Type, then sorting by Power you can clearly see these relationships but also this view includes PP (the amount of times a move may be used) and this somewhat correlates to high PP having a more divided Charge Bar in PoGo.
Category (Special/Physical) doesn't really serve a purpose in PoGo because the original games had, attack and special-attack, defense and special-defense, which is not exactly the case in PoGo.

So if you're worried about having transferred a Twister Gyarados because "they may buff it in the future", I wouldn't be too worried about it. If they stay true to the original games, Twister will be UNLIKELY to receive a significant buff because it was so bad in the original games. Of course, Niantic being Niantic, they could certainly do it if they wanted to, but I don't see good reason for them to justify deviating from the main series games in this particular area. Even a lot of the move animations are derived from the original games.

That being said, some of the moves had secondary effects (for example, Overheat would sharply lower the users special-attack stat after use), so really it would likely be used once per battle, before switching out that mon. So if you planned on using Charizard, for example, to sweep several mons in a row, Fire Blast was a good option because it has consistently high damage with decent accuracy, then use Overheat on the last one. So in case some of these mechanisms are implemented in PoGo in the future, make sure you read the description of the move, don't just look at the Power/Acc./PP because it may be misleading.

So when I read comments on here like "They should've [nerfed] Earthquake", I think to myself "no way!", because Earthquake was amazing in the original game, 100 Power / 100 Acc and no recovery time!! Granted it was terrible against flying types (or even Gengars with Levitate) but when it did connect it was usually a win. I remember the first time Lance's Gyarados hit my Jolteon with Earthquake... Instant KO from SE type coverage combined with Gyarados' deadly high attack stat for a physical category move.