Firstly, 90 HP is too low for a Stage 2...
Secondly, WTFness - W type uses F energy?
It's not that bad overall, but the 3 coin limitation can be a pain, especially if you're no good with coin flipping and/or when you're up against a 140+ HP Stage 2 ex (let's save Whailord ex for now). Still, I'd say the Kabutops ex is better to use - but this is OK at that time considering the ex's weren't out then.
7/10 - if you're good with coin flipping.
Don't use it at all if you have completely no control over your coin flipping - it IS a skill after all!
(My highest record was 84 heads out of 100 flips with a tested FAIR coin.)