Lysandre and Boss's Orders cannot be included in the same deck. This is similar to the rule that says Professor Juniper, Professor Sycamore, and Professor's Research cannot be included in the same deck.
Source: TPCi Announcement (2020-04-16), TPCi Rules Team (2020-04-30)

Relevant cards

Note: All applicable cards may not be listed below.
SWSH2_154
SWSH2_154
SWSH2_189
SWSH2_189
SWSH2_200
SWSH2_200
XY2_104
XY2_90