Since Eeveelutions are always popular, here's an idea for a deck based around Espeon and Leafeon that is used to demonstrate Special Energy, split evolution chains, and Special Conditions:
Basically the idea is to start off with Stantler. If they don't have one, hopefully they drew a Pokemon Collector. The player wants to try and get his or her bench set up for evolution by turn 2. Eevee can use its Call For Family Attack as well, though it nets one fewer Pokemon and leaves your Eevee vulnerable.
The main attacker in the deck is Leafeon with its Miasma Wind attack, though Soothing Scent can be used in a pinch. The goal is to inflict multiple Special Conditions on the opponent's Pokemon and do either 100 or 150 damage each turn.
Of course, the fire weakness of Leafeon is not good in the current Meta, so the player would be encouraged to work on setting up an Espeon Prime since its Poke-Body lets it copy the attacks of a benched Leafeon (or vanilla Espeon). Vanilla Espeon is in the deck to knock out any Pokemon that are near death with it's Solar Suggestion attack.
Roserade is in the deck to provide a consistent way to apply Special Conditions to the opponent's Pokemon turn after turn. Not only does this help with using Leafeon's Miasma Wind, but it can be deadly to a high-retreat Pokemon in itself.
Magby is in the deck because it can auto-burn, but it's not essential to the deck's strategy and could be replaced with something else quite easily.
Shaymin is in the deck for the occasion when you would need to attach to Roserade and another Pokemon on the same turn. You would attach to Roserade and then use Shaymin to move the energy to another Pokemon in play.
One of the nice things about the deck is that it lets the teacher teach about three of the advanced game rules: Attaching Rainbow Energy to Roserarade, What Special Conditions can be applied at the same time, and moving Rainbow Energy with Shaymin. (Cheat sheet: Rainbow is all types when in play, so it causes both of Special Effects to be applied at the same time; Burn, Poison, and Confusion can all inflict a Pokemon at the same time, but a Pokemon can only be either Confused, Asleep or Paralyzed at one time; When moving Rainbow Energy that is in play, a new damage counter is not placed on the new Pokemon since Rainbow Energy is being moved instead of attached from the hand.)
Pokemon Communication is used to get the Pokemon you need right at the moment in exchange for the Pokemon you didn't need. For example, say your hand is Roserade, Roselia, Rainbow Energy, Pokemon Communication, and Energy Exchanger. You have an active Leafeon with no energy attached and a benched Roselia as you start your turn. You could evolve the Roselia to Roserade, attach the Rainbow energy, and use the communication to trade the Roselia for Shaymin. This allows you to use Shaymin's Poke-Power to move the Rainbow to your active Leafeon. In this way you can turn a "Pass-Turn" into attacking for 100 damage (plus 10 for poison between turns).
Energy Exchanger is used in a similar way to trade out an energy you don't need for exactly the energy you do need. Interviewer's Question is also used to get the energy the player needs at the time, though it can be less effective.
Super Scoop-Up and Seeker are both used to recycle your benched Roserade and its Special Energy. They can also be used to return a Shaymin to hand to re-use its Poke-Power, or to heal a damaged Pokemon on the bench (active as well in the case of Super Scoop-Up).
The 3 Revive are mainly in the deck to recycle Eevee that have been knocked out. They could also be used on any other basic, though. The reason there are more Pokemon that Evolve in the deck than there are Eevee is mainly because there are Revive in the deck. In the same way, Recycle energy can be attached to any Pokemon that is near being knocked out to make sure it's returned to the hand when it's knocked out.
I think this deck could use a little more work, and I welcome any suggestions on improving it, as I think the idea is a good one for teaching.
Pokemon (22)
Stage 1 (9)
2 Espeon Prime
1 Espeon
3 Leafeon
3 Roserade
Basics (13)
4 Eevee (Call For Family)
3 Roselia
2 Stantler
2 Magby
2 Shaymin
Trainers (26)
Items (13)
4 Pokemon Communication
3 Revive
2 Super Scoop-Up
2 Energy Exchanger
2 Pokemon Catcher
Supporters (13)
3 Pokemon Collector
4 Professor Oak's New Theory
4 Seeker
2 Interviewer's Questions
Energy (12)
4 Rainbow Energy
2 Rescue Energy
3 Grass Energy
3 Psychic Energy
Basically the idea is to start off with Stantler. If they don't have one, hopefully they drew a Pokemon Collector. The player wants to try and get his or her bench set up for evolution by turn 2. Eevee can use its Call For Family Attack as well, though it nets one fewer Pokemon and leaves your Eevee vulnerable.
The main attacker in the deck is Leafeon with its Miasma Wind attack, though Soothing Scent can be used in a pinch. The goal is to inflict multiple Special Conditions on the opponent's Pokemon and do either 100 or 150 damage each turn.
Of course, the fire weakness of Leafeon is not good in the current Meta, so the player would be encouraged to work on setting up an Espeon Prime since its Poke-Body lets it copy the attacks of a benched Leafeon (or vanilla Espeon). Vanilla Espeon is in the deck to knock out any Pokemon that are near death with it's Solar Suggestion attack.
Roserade is in the deck to provide a consistent way to apply Special Conditions to the opponent's Pokemon turn after turn. Not only does this help with using Leafeon's Miasma Wind, but it can be deadly to a high-retreat Pokemon in itself.
Magby is in the deck because it can auto-burn, but it's not essential to the deck's strategy and could be replaced with something else quite easily.
Shaymin is in the deck for the occasion when you would need to attach to Roserade and another Pokemon on the same turn. You would attach to Roserade and then use Shaymin to move the energy to another Pokemon in play.
One of the nice things about the deck is that it lets the teacher teach about three of the advanced game rules: Attaching Rainbow Energy to Roserarade, What Special Conditions can be applied at the same time, and moving Rainbow Energy with Shaymin. (Cheat sheet: Rainbow is all types when in play, so it causes both of Special Effects to be applied at the same time; Burn, Poison, and Confusion can all inflict a Pokemon at the same time, but a Pokemon can only be either Confused, Asleep or Paralyzed at one time; When moving Rainbow Energy that is in play, a new damage counter is not placed on the new Pokemon since Rainbow Energy is being moved instead of attached from the hand.)
Pokemon Communication is used to get the Pokemon you need right at the moment in exchange for the Pokemon you didn't need. For example, say your hand is Roserade, Roselia, Rainbow Energy, Pokemon Communication, and Energy Exchanger. You have an active Leafeon with no energy attached and a benched Roselia as you start your turn. You could evolve the Roselia to Roserade, attach the Rainbow energy, and use the communication to trade the Roselia for Shaymin. This allows you to use Shaymin's Poke-Power to move the Rainbow to your active Leafeon. In this way you can turn a "Pass-Turn" into attacking for 100 damage (plus 10 for poison between turns).
Energy Exchanger is used in a similar way to trade out an energy you don't need for exactly the energy you do need. Interviewer's Question is also used to get the energy the player needs at the time, though it can be less effective.
Super Scoop-Up and Seeker are both used to recycle your benched Roserade and its Special Energy. They can also be used to return a Shaymin to hand to re-use its Poke-Power, or to heal a damaged Pokemon on the bench (active as well in the case of Super Scoop-Up).
The 3 Revive are mainly in the deck to recycle Eevee that have been knocked out. They could also be used on any other basic, though. The reason there are more Pokemon that Evolve in the deck than there are Eevee is mainly because there are Revive in the deck. In the same way, Recycle energy can be attached to any Pokemon that is near being knocked out to make sure it's returned to the hand when it's knocked out.
I think this deck could use a little more work, and I welcome any suggestions on improving it, as I think the idea is a good one for teaching.