Leafeon: not too shabby, pretty decent first attack, like a stronger version of Energy Crush, would be effective against many decks that dont discard all energy, ie Raging Bolt, and unfortunately the second attack is 10 damage short of OHKOing it, but it could definitely work against Charizard, if they have 3 Energy on the board or Regidrago if they have 5
Flareon: with its first attack it's playing more of a supporting role in helping your Benched tera Pokémon but unfortunately the damage of the first attack isn't too great. 280 is a very good number and I wouldn't worry too much about the side effect, since you should've been able to set up a Benched Pokémon so either you retreat or die
Vaporeon: doing 60 to each ex sounds fun until you remember half of them have bench protection so that's a bad attack to use. If it did, it would've been useful paired with the second attack so it would've put Charizard and Dragapult in range but it doesn't do that.
Glaceon: the first attack is not very good, the second attack sounds at least interesting but you know what else instantly KOs opponent's Pokémon with exactly 6 damage counters on it? 6 damage counters.
Jolteon: deals max 210 for 2 energy which isn't too shabby, that's decent against Ogerpon decks. It's also the best user of the 280 one turn recharge attack since it has no retreat cost.
Espeon: I'm a fan of espeon it's one of my favourite Pokémon, and these attacks are... Odd? I could see them work though. Shuffling every evolution Mon back into the deck is huge. I feel like it could work as a one-off in Gardevoir decks if they run dark for Munkidori and add Luminous, then it would cover some threats that the small boys struggle against
Sylveon: this one's already out soon, idk if people have been using it tbh. Angelite sounds pretty powerful, like, f- your Pidgeot or Gardevoir or Baxcalibur or whatever
Umbreon: reminds me of Ultra Beasts which I think they should bring back, but I'm not sure how strong it will be. You're taking (only) 1 Prize card while ruining your own board state and keeping your opponent's fully intact, so unless there's some control deck that blocks your opponent from doing anything while you try to pull this off continuously, I don't think it'll be that useful. Maybe Dusknoir or something idk