Try and create good new abilities and moves. Realestic or broken if you want
>Thunderstorm
In this, lightning moves receive a 50% buff and there is a 20% chance that the non-water types will be paralyzed, 40% chance for water types
>Hurricane
Flying types receive a 50% buff, all entry hazards are cleared and cannot be placed during Hurricane. There is a 20% chance of a random Whirlwind for all non-flying types
>Acid Rain
New Poison signature move
Poison type receives 50% buff, all non-poison types receive 1/16 damage, grass and fairy receive 1/8th damage. 10% chance that non-poison and non-steel types will be poisoned, 20% chance for fairy and grass types

Abilities
>Corrosion
Poison types now do neutral damage to Steel and ground types. Acid Rain now does 1/16th damage to Steel and ground types.
>Run-off
Poison types do super effect damage to water types and all water type moves become poison type moves when hit with poison move. Rain cast by Pokemon hit with a poison type become Acid Rain