Gray lost to Bickslow because he got tricked and he coudn't use any magic. In a far fight Gray would easily beat Bickslow and he would beat Freed.He's stronger than Mira with his new power up
Mira survived azuma's time bomb without MP. Gray survived Bickslow's little blasts. Mirajane's is much more impressive.
Freed has agile CQC, unless you see gray moving as quick as Freed in CQC exchange, Gray isn't winning without his powerup.
Gray is smart though, I can see him somehow defeating freed, but no world do I see him beating Mirajane.
Gray will get pummeled to the ground like how Elfman defeated Monsieur Sol from Phantom Lord.