Could I get squid for offering members a free trial?

People are pretty loyal to their gyms. You should advertise where potential clients will see your ad, and offer something compelling. (All gyms have free trials.) If people have signed a contract with their current facility, it's unlikely they will break it, unless you buy out the contract.... and that wouldn't be cost-effective to you.

It's really not ethical, but you could find out -- perhaps at the police dept. -- if you're allowed to stick a flyer on car windshields in gym parking lots. (May not be allowed, since it's private property.)

On Canton Road there are two competitive fish restaurants. The original restaurant paid to have a billboard ad in the parking lot of the other restaurant! You could look into something like that.

not specifically targeting other gyms members but you can compete with adds in the same paper etc you have to be cleaver u cant just straight up go to another persons gym and tell the to leave for your better deal.

not sure about a squid, probably goldfish tho

Squid is good, if you prepare it well.