Well, if it absorbs an Ice move that goes before another move, the Substitute has already done its job, and against things that are either set-up+attack or straight-up stall it could be quite the nice combo.
I have an idea Hack_Guy. The priority should be the sum of the linked moves' priorities. So, Spikes + Whirlwind link for example will be 0 + (-6) = -6 priority for the link. Fake Out + Last Resort will be 3 + 0 = +3 priority.
There is something horrifying about being able to combine Feint with literally anything to turn it into Extreme Speed, let alone combining Extreme Speed with something.
Worse yet, Protect is +
4 Priority, letting you Protect yourself and go before almost anything in the game.
Dementedly, Helping Hand will let you push another move past any Protect that isn't supported by its own priority, and if you're faster any Protect that isn't backed by Feint or Extreme Speed.
Then you get a Prankster using Roar (-6, goes up to -5 from Prankster) and Helping Hand (+5, goes to +6 from Prankster) and now you have
+1 priority Roar.
Since Focus Punch is actually only -3 Priority, combining it with Protect turns it into +1 priority, +2 if you're a Prankster.
Not saying this isn't an
interesting solution (It does have some advantages), just pointing out that the implications are kind of contrary to what Hack_Guy has been trying to achieve.