The Psychics lost none of their OPness in the Generation 2 in-game simply because none of the countermeasures took hold - among every single in-game trainer in the game, there's 2 of Umbreon, Murkrow and Houndoom and 3 of Sneasel to defeat, meaning there's nine Pokémon in the entire in-game portion that are immune to Psychic. Furthermore, Ghost moves are physical and thus weaker on the ghosts, which are also nearly nonexistent outside of Ecruteak City. Bugs are still shafted on STABs, with only Heracross getting a notable one (and it matches up very poorly against Psychic-Types due to being part Fighting). It's probably the reason why everyone and their mother has a Poochyena/Mightyena in Gen 3. Abra is easily the top in Gen 2 because it can topple the few random Steel-Types with Fire Punch and just STAB through anything else.
Also, Shuckle is a cut above the likes of Unown and Tyrogue simply because it comes at a decent level as a free gift and Defense Curl + STAB Rollout hurts even if your attack stat is garbage. Shuckle also has the bulk to pull that manuever off from time to time. It -is- trash for sure, but still even remotely usable.
In RSE, I'd argue Aron to be somewhat more useful than Skarmory - although its typing is not that good on the defense, it learns much better attacks like Earthquake and Double-Edge. It even has Thunderbolt to deal with some of the Water-Types if you really want to. Treecko is also one that looks strong and fast on paper, but it's too frail to take on most Pokémon it doesn't have a type advantage over, many Water- and Ground-Types have a type that cancels their grass weakness in Hoenn, it doesn't have any good moves outside of Leaf Blade and -maybe- Dragon Claw if you backtrack for it and Shroomish, Roselia and Gloom are at various points in the game as a better Grass-Type option with not only more attacking options, but also status moves to support your team with in case they don't have type advantage. It even struggles to defeat the early game Wurmples + evos and Taillows. But if you really want to forgo any utility moves offered by the other Grass-Types and two starters leagues ahead of it just to bop Wallace's Whiscash, go for it.
Also, Shuckle is a cut above the likes of Unown and Tyrogue simply because it comes at a decent level as a free gift and Defense Curl + STAB Rollout hurts even if your attack stat is garbage. Shuckle also has the bulk to pull that manuever off from time to time. It -is- trash for sure, but still even remotely usable.
In RSE, I'd argue Aron to be somewhat more useful than Skarmory - although its typing is not that good on the defense, it learns much better attacks like Earthquake and Double-Edge. It even has Thunderbolt to deal with some of the Water-Types if you really want to. Treecko is also one that looks strong and fast on paper, but it's too frail to take on most Pokémon it doesn't have a type advantage over, many Water- and Ground-Types have a type that cancels their grass weakness in Hoenn, it doesn't have any good moves outside of Leaf Blade and -maybe- Dragon Claw if you backtrack for it and Shroomish, Roselia and Gloom are at various points in the game as a better Grass-Type option with not only more attacking options, but also status moves to support your team with in case they don't have type advantage. It even struggles to defeat the early game Wurmples + evos and Taillows. But if you really want to forgo any utility moves offered by the other Grass-Types and two starters leagues ahead of it just to bop Wallace's Whiscash, go for it.