This forum game has damage calculations like the games, and incorporates Natures and Abilities. All IVs are maximized.
Pokémon are all at Level 100 and treated as such, and thus can use all their level-up moves, though you can purchase TMs and HMs.
In order to catch Pokémon you have to first weaken them then you must throw a Pokéball to successfully catch it. Although sometimes this may not work and the Pokémon might escape. You have to throw another Pokéball to try to catch it again.