Not sure on the size of your pleco, but mine was about 8" to 10" when I had to move him.
I used a large plastic pitcher (for iced tea). But mine was partially drained. Just slowly moved up to him and scooped him out. But it did take a few times to actually get him. They are crazy strong and fast when they want to be.
plastic container is by far the best way.. i just toss my dollar store pitcher in the tank and after a while my pleco hides in it.. then i just put the cover on and its done..
you can pick them up by hand, watch that fin though that dorsal spine.. if yer "scared" of hurting him/yourself the plastic pitcher is the way to go.. its just easyer..