Strong Slammers have a similar appearance to normal Slammers, being red and having the same shape, but they have what seem to be white-lined cracks all over their body. There are also several areas around the Strong Slammer where it is tinted a darker red than the rest of the body.
Like Slammers, Strong Slammers attack mainly by clapping their hands together to send a sonic wave at Luigi. Strong Slammers are much tougher to vacuum up into the Poltergust 5000 requiring more effort. It is also wise for Luigi to try and vacuum up more than one Strong Slammer at a time.