If Garp's people decided to go rescue him, it'd be SWORD and a few "good apple" Marines, not the organization as a whole. Akainu wouldn't greenlit the operation, so no Admirals would be sent either. The WG as a whole wouldn't let the PXs and Seraphim be used for it.
It'd be a small squadron, maybe led by Sengoku himself, capped at Smoker's and Koby's powerlevels.