A couple quick rules questions

[wonderer]

If you have a card effect that removes the highest stage pokemon, and this effect is played on a Lv. X, my understanding is that the highest non-level x gets removed, and then the level x must be discarded because it no longer applies. Is this correct? If used against a basic Lv. X pokemon, do other effects of the attack get used or no?

How does Electrode's (SW #26) energy shift work? My understanding is that it would ONLY get triggered during my turn, and therefore would only take effect if knocked out by its own or another of my pokemon's attacks. Correct or no?

 

[PokePop]

First question: No. That's not how it works.
You really need to ask about a specific effect, though.
For example, Devolutor can't be used against a Level X Pokemon at all

However, for effects that can be used against a Level X Pokemon, the Level Up card goes to the same place that the lower level card goes.
If used against an Unevolved Pokemon that is a Level X, there is no evolution stage to remove, so that's not a legal target.

Second question: Not correct. It would be correct per the wording on the card, so you have read it correctly.
However, Pokemon issued an errata, a correction, to that cards text. Here it is:

Energy Shift (Electrode - DP:Secret Wonders)

* Electrode is receiving errata for the card to reflect that its Poké-Power can trigger when any attack Knocks Out Electrode, not just during its owner's turn. "If Electrode would be Knocked Out by damage from an attack, you may use this power. Electrode isn’t discarded. Instead, attach it as an Energy card to 1 of your Pokémon. While attached, this card is a Special Energy card and provides every type of Energy but provides only 1 Energy at a time. (Has no effect other than providing Energy.)" (Dec 6, 2007 PUI Rules Team; Jan 29, 2008 Pokemon Organized Play News)

You should really get familiar with all of the errata that have been made. A player is not required to have a reference of card errata so you might get taken by surprise or get taken advantage of if you're not aware of them.

Here they are: http://compendium.pokegym.net/compendium-lvx.html#c3