fire spin - if the enemy pokemon die while is effected by fire spin next pokemon that come in battle still trapped (effect can be lost only by death of fire spin user or after 4-5 turns) (TESTED)
whirpool - i guess the same bug exist with that move too (not tested yet)
Whirpool vs Gastrodon (Storm Drain) - Move not damage gastro and raise his sp atk but stil trap it and lose hp every turn. (TESTED)
also something more i dont know if is bug or not is non damage grass moves vs sap sipper is just immune dont raise attack (no idea if this is bug or not)