i don't really agree with that, investing in tankyness (HP- Def -Sp Def / natured ) allows you to resist pretty much any hit that is not critical. ( my spinda still haven't die yet from any move so far, eventually it will happen and i'll edit this )
So basically if you are running lagging tail the only hit that matters is the first one, as long as you survive the first hit you can lock the opposite monster, i have been using my set a lot lately and it works incredible well.
Turn 1 you take the hit and trick into lagging tail, now the alpha is holding lagging tail, this works as a secure for speed, no matter what, it will always hit second, so you don't really care if he boots its stats even after the contrary effect get reversed.
Turn 2 you will be faster than the alpha ( cause is holding lagging tail ) so you can freely skill swap and lock it.
if the alpha does a move like SS, DD, or any other boost stat move or support move you can Encore it ( cause it will be holding the lagging tail ), so after the encore you can skillswap disable for some damage before going back to your breloom/smeargle/parasect or any other spore/soak user according to the situation.
i think this set is super optimal for ppl that doesn't run rock smash, flash or strengh on their Spinda.