It should be a.teleport("jump"), with quotes, otherwise it'll have an error and won't execute. If the skill does no damage, I prefer to put it in a yanfly skill core notetag rather than the damage formula, for nicer organization.
The animation is most likely because you have a cast animation configured in YEP Battle Engine Core for one of your skill types.
@ssalum Make sure everyone has an attack range defined, by a combination of the "attack" skill and the weapon's range- I'd suggest starting with the demo project in the first post, then replace the SRPG_core with my version to make sure things work. Setting up the system in a project isn't complicated, but the demo gives a lot of good examples of how to do common things like different types of attacks, cutscenes, and combat events.