>>35689930Not very. Any doubles metagame that allows both Lugia and MegaFug will run into a ton of other issues. For one, Lugia isn't that great in doubles Ubers in general, being totally unranked in viability threads. Yveltal and Lunala are among the most used mons in that format, and they shit on Lugia in general.
Not to mention M-Fug isn't half as broken in doubles as it is in singles; it and the primals are all about equal in that format thanks to their weather control and team support; the primals are slightly better thanks to not taking up a Mga slot you could potentially use on Gengar (which also shits on Lugia). It is so much easier in doubles to switch out to your primal and reset the weather to something else. So in addition to being a useless team member, Lugia's bulk can be totally cut off in the same turn its multiscale breaks.