yea i agree, wifi does prevent both players from being at the absolute best. Now, if you WANT to stop people from ledge stalling with shiek, here is what you do:
1. get near the ledge
2. when the foe lets go of the ledge and travels a few feet downwards
3. run off and reverse tether grab with your chain
4. they will notice this and try to UP+ B, it wont hit you because of you invincibility frames.
Lots of characters have answer to stop the ledge stalling, some are easy(ddd) others are hard(jiggs) and it just takes time to figure out what exactly u need to do to stop it..