I expect for every fast and charge move that a pokémon can currently learn be accessible in PvP matches only. This would probably make mew the best overall option.
Each pokémon must be unique. So you can’t use the same species in a single match.
Battles should be able to be performed anywhere and limited if you’re not at a gym.
There should be a collective max CP cap for all 6 pokémon per tier. The chart below is just a mock-up but you get the idea.
|Tier Level||Tier Group||Collective CP Total|
|Tier 1||Babies, marrill, shuckle||3,000 CP|
|Tier 2||Starters, plusle, sudowoodo, butterfree||7,500 CP|
|Tier 3||Raichu, absol, jynx, bayleef||9,000 CP|
|Tier 4||Gengar, jolteon, poliwrath, scizor||20,000 CP|
|Tier 5||Machamp, entei, mewtwo, dragonite||30,000 CP|
This chart is just to give an example based on TDO against a tier 5 raid boss. Pokémon names used are not fixed to each tier group.