The best moveset for Alcremie in the current competitive meta typically features the moves Decorate, Protect, Dazzling Gleam, Helping Hand.
In the Pokémon Champions meta, Alcremie can be countered by exploiting its weaknesses (poison 2x, steel 2x) and using effective check/counter teams.
The best item for Alcremie is typically Kebia Berry, based on high-level tournament and ladder stats.