I have plenty of switch from my old cards, I ordered 2 Lysandre, 3 N, 4 Ultra Ball, 4 Sycamore, and 2 Vs Seeker (I pulled one the other day).
Bold text added for emphasis: I just wanted to make sure you realized that
VS Seeker is a pretty important card. I could be wrong, but I believe most competitive builds run a full play set, so you ought to try for one more. If you find any at a good price,
Shaymin-EX (ROS) is the one current expensive staple. There are very few decks that run without it, and the only one I remember being competitive is the one based on
Greninja BREAK. Again, I may be unaware of recent changes as I tend to learn from the results of the latest events, not playtesting before hand. ^^'
It is possible
Shaymin-EX could rotate out, but it released in
XY: Roaring Skies so it would require a higher-than-normal (but not unprecedented) six sets rotate out all at once. I think some of the cards already listed (like
VS Seeker) are only "rotation resistant" because of reprints in
XY: Roaring Skies. Yet another thing I cannot guarantee, but Japan has seen some additional reprints lately, making me think
Shaymin-EX isn't going anywhere.
Some "loose" staples to consider are
Acro Bike,
Battle Compressor and
Trainers' Mail. Unfortunately I cannot assure you that these will not rotate.
Acro Bike is from
XY: Primal Clash which would make for five set cut; not the most often seen but well within reason.
Battle Compressor is in
XY: Phantom Forces so most expect it
will be cut, however I believe it was reprinted in Japan so we might be due a reprint here.
Trainers' Mail should be safe as it was reprinted in
XY: Ancient Origins, which is only four sets ago (and one of those is
Generations which is a sort of "bonus" set to celebrate the 20th anniversary of Pokémon).
