Short answer: No
Long answer: Nooooooooooooooooooooooooooooooooooooooooooooooooooooo
Really long answer:
With a pitiful 60 SpAtk and only Grass, Ghost and Hidden Power as coverage, Leafeon is one of the worst Special Attackers in the entire game. It's aweful, horrendous, hideous, poor, weak, pitiful, etc.
It is an extremely bad Pokemon to use competitively, almost anything fully evolved could and would do its job better. Seriously, don't use it.
The best possible set would be:
Leafeon @ Choice Specs
EVs: 252 SpA / 4 SpD / 252 Spe
- Giga Drain
- Shadow Ball
- Hidden Power [Fire]
- Hyper Voice