Yo, everyone knows that comp, is expensive and sometimes you guys just wanna test some mons. PTS allows you to do that since you have access to the /debuf commands to gib pokemons and alter everything about the pokemon.
Downside of this? Maybe server hosting values? Dunno.
edit: Yes teambuilding websites exist, but can you test in the same environment as in pokemmo on those said websites? With gen7 abilitys + stats on some, gen3 on some moves(outrage), no HA, no legendaries and have a community dedicated to testing in them with this conditions?