Don't use a net, they will get hung up in it, ending with an underwater battle freeing them at the least, with damage & death to the fish at worst, along with your fingers getting poked & bleeding.
I've moved large plecs several times, I have a 15", two 12" & a 9" common. This may sound stressful, but actually it is less stressful then netting, chasing & scooping, or any other method I've tried for large plecs. Get a sturdy pair of leather palmed gloves. Drain the tank down to the level that the top fin of the plec is almost showing. Put on the gloves, make sure they are good & wet. Grab the plec from the top, just behind the eyes, by the bony girdle just behind the eyes. Hang on tight, but try not to push down too hard, the fish will be kicking its tail back & forth. Lift the fish, and put it in a bucket for a longer transport, or just carry it if the tank is across the room. If you grab too far back you will be grabbing muscle, and will not be able to hang on.
I've done this several times over the years, with no damage to fish or myself, other than getting very wet. The 15" plec grunts like a pig when he's/she's out of the water, so don't be surprised at any unusual sounds.