Shieldstop or Pivot out of Sheik's grab range and do things. Attack from behind, mix up jab pressure timings (and hit confirm from jabs/drop shield confirm), not necessarily in a random way, but as a judgement of spacing and options. Did I mention that jab approaches with Falcon are pretty decent, even if they aren't as good as some other top tiers jab approach? Dash dance a lot, and be ready to counter attempts to hit this. Low aerials -> jab or dash away to punish shield grabs, and retreating aerials are also good. AC bair, and to a lesser extent, uair give you less telegraphed/setup options. He might try to punish spaced utilts or ftilts, neither or which are really going to work, and you can also use these after a spaced jab in place of the next hits of a jab combo. If it hits, as percent goes up, trying to shield grab will put her in bad positions. Try to avoid spotdodging, when you need one of the non-advanced technique defensive options, roll is usually better. Falcon doesn't really get punishes from spotdodging. Sheik's spotdodge last 10 frames less than yours.
