252 SpA / 4 Def / 252 speed
Timid
Terra Fire
-Seed Flare
-Dazzling Gleam
-Terra Blast
-Earth Power
I don't think locking yourself in to specs is good for shaymin. I think it's better to fish for Seed Flares first, since then you can do things like pop Gholdengo's balloon, not waste a tera to actually use Tera blast, etc. Weirdly enough, I think Shaymin could actually beat gliscor 1v1 as long as it's not the acrobatics set and you use Synthesis. Tera Fairy Dazzling Gleam would be probably funny for those Tera dragon manaphys running around.