Would this Jellicent be a threat?
No. No no no.
Offensive Jellicent is quite rare, and is outclassed by more Defensive Variants - the ones with Recover/ Scald / Shadow Ball / Taunt or Toxic or something like that. Offensive Variants are bad, though the Water Spout Choice Specs Variant is usable for the surprise factor - but it requires Rain Support to be a true threat. Gen 6 nerfed weather, so even that isn't as viable. The reason why pure offense Jellicent is bad, is it's base 85 Special Attack is hardly enough to be threatening in the OU environment. Water Spout + Choice Specs + Rain was very threatening back in Gen 5, but now as long as they can stall it out, the power drops tremendously. However it is still a viable set if you want to go for a Specially Offensive Jellicent