So I decided to create a competitive team and I need some tips pokebros, can you help me pls ?

So far I have a /vp/oreon fully trained:

-31 IVs in SpAt
-252 EVs in SpAt
-252 EVs in Hp
-4 EVs in SpDe

Hability: Hydration

Nature: Mild

Item: dunno, I was thinking in leftovers

Moveset:
-Toxic
-Rest
-Hydro pump
-Ice beam

Suggestion for the rest of the team, items, natures, habilities, strategies ? I dont want to keep losing to japanese people in wifi matches

>inb4: pls respond