Some ideas on future third stage Pokémon

-Additional starter Pokémon: Similar to Simis, these secondary starters can work as replacements for species that are not obtained as starters. This idea would be good, because currently the only major third stagers are sadly starters.

These species can be at the lower end of starters, around 525 BST. They can be obtained in wild, or given after a specific period.

-Additional trade Pokémon: Not an idea I personally like, but trade Pokémon have been the primary drivers of three stage Pokémon for a long while. As trade evolutions have been declining in the last generations, this can bring them back to life.

-Additional three stage Electric-types: Another major third stage presenter, these can be expanded to make Electric-type more viable.

More specifically, Electric-type can have a honorary starter archetype, as an expansion to what we currently have.

-Additional three stage Psychic-types: More successors to Abra can be given. Psychic-types are missing powerful common species recently, so this can be a good way to bring back life.

-Additional three stage Steel-types: More successors to Magnemite can be given. Steel-types need more representatives, so this will be helpful.

-Additional three stage Ghost-types: More successors to Gastly can be given.

-Additional three stage Fighting-types: More successors to Machop can be given.

-Additional three stage Water-types: More successors to Poliwag would be... bad, but better than endless fishes.

-Other ideas:

1. New archetypes: Rather than expanding upon existing archetypes, completely new archetypes would be better. These can be utilized on underutilized types, such as Flying, Bug etc.
2. New tiers in-between standard Pokémon and legendaries: Currently common Pokémon can go up to 540 BST, while legendaries can go down to 570. More varied archetypes in this 30 BST gap can be created, similar to Archeops or Togekiss.
3. Pseudo-ubers: Similar to pseudo-legends, these will be Pokémon who have stats around 601-680 range, working similar to Ubers. These Pokémon will appear as post-game challenges, and be banned in initial tournaments, becoming legal after the second year.
4. Pseudo-sub-legendaries: These Pokémon will cover the 570-599 range, mimicking sub-legendaries. These Pokémon will be semi-final bosses, appearing before the showdown with the pseudo, around 7th badge or so.
5. Pseudo-Megas: Similar to the conventional trade evolutions, these would be species who have highly powered middle stages that can work competitively and in-game, but will have upgraded third stages that can be more varied. These species would go around pseudo-legendary level at max. The idea behind them would be to abuse Eviolite without creating cross-generational evolutions.
6. Psuedo-Mythicals: Similar to above, but a bit different, these species would have certain event-exclusive items and methods that would allow them to evolve to their true form, but would remain usable in their current situation.
7. Terrain bosses: Using the lore of Haxorus and Aggron, these would be powerful third stage Pokémon that would work similar to Totem Pokémon and act as mid-bosses. Their middle stages would be around conventional pseudo-legendary/starter middle stage level, while themselves would be around 525-540 range. They would be found in wild through special means.