AHHHH! SPAM!!!!!!
*ahem*, well sigilyph is an amazing weather staller, magic guard so no damage from weather or statur or leech seed.
and the best 2 moves ever for stall sweep, cosmic power and stored power.
cosmic power, raises def and sp.def by 1 stage so you can build up defences
Stored power: 20 base power 100% acc, extra 20 per stat boost, so after 1 cosmic power 60 base power (+1 to def and +1 to sp.def) after 2 cosmic powers 100 base power, and after the full 6 cosmic powers, 260 base power 100% acc psychic move.
it also gets roost and has good defences and speed anyway, in the final slot you can choose between whirlwind to stop other phazers and dark types from walling, air slash for another attack, psycho shift if you use toxic or flame orb to burn/poison the opponent.