Question

Help

Answer 1

well -

Unlike in Generation I, Fissure can affect a Pokémon whose Speed stat is greater than the user's current Speed stat. However, it cannot affect a Pokémon of a higher level. The accuracy of Fissure depends on the level of the user and the level of the target and is worked out with the formula: Accuracy = ((level of user - level of target) + 30)%. Fissure ignores all changes to accuracy and evasion stats. bulbapedia

so its that or your using it on a flying type or a pokemon with levitate

Comments

or a ghost (Horn Drill & Guillotine)

Answer 2

Fissure,horn drill, gilloutine etc (1 hit KO moves) won't affect a pokemon with the ability: STURDY