Are you and/or your bandmates fairly new to playing in a band?
Speaking with my sound engineers hat on
this is the eternal problem and can only be solved by discipline (no I don't mean taking the other guitarist 'outside'). Depending on the line up (mostly drummer/no drummer) you need to try to play as if you didn't have a PA until you all learn to balance yourselves to the others, if it's somebody else lead break/vocal lay back a bit and step up when it's your turn. Watching old school Bluegrass bands do the microphone dance is instructional but its more than that, it's really about learning to listen.
But I suspect your problem is more that he has an amp on stage and you don't have a sound guy (forgive me if I'm wrong here) so you set the monitor level for your guitar and then he plays louder (I used to gig fairly regularly with another guitarist who did just that).
With my guitarist's hat on, you need an amp
. Tele (and Strat) pickups are relatively low output but any half decent electric guitar amp will have enough gain to make up for that, if you have humbuckers turn it up to 5, if single coils (like my '61 Strat) turn it up to 8, it's only a problem if you need to swap guitars mid set.