Some people are hyping these cards up way too much. For the most part, we already have most of these effects already.
Flareon V-Max: Sandaconda but worse. It's 3 prizes and 2 attachments - at least not 3 - which means you need to use Houndoom and Single Strike Energy and the tool to attack. And given the hefty line of support you have to run, you won't be hitting a full 300-500 until the late game. Even Sandaconda, that plays 26-28 energy sometimes finds itself hitting for 60-120 damage early game, I know because I play the deck.
Vaporeon V-Max attack is Dark Union from Zoroninja, and like Zoroninja, using your attack to setup is a waste of damage and tempo. Unless the attacker you're setting up is so powerful, you're giving your opponent a dead turn to setup. Stick to Frosmoth/Melony.
Jolteon V-Max hits for a single L with its tool, and is yet another spreader. 100/100 for L is crazy stupid, so what's the deal? Well, that Fighting weakness. Still, I can kinda see it work as THE electric deck post-rotation, given that it can use Cheryl and Rose for good support.
Espeon V-Max is bad support. Maybe some deck includes it as a 1-1 line but that's it.
Glaceon V-Max is... Eh. We already have that effect on Zamazenta V , and between Phoebe, Aegislash V, 4 Boss Orders and Escape Rope, and 90% of bench hitters, we don't lack options to hit through its immunity. Hell, even Urshifu Single Strike Hit goes through its immunity.
Umbreon V-Max is crazy stupid - as a support mon that is. Eternatus and incense compatible, and future searchability from Single Strike support? Yes please. My only issue is that we are losing Giovanni's exile as soon as we get these, so re-using it is out of the question, but being able to Marnie and then gust is about as broken as plays go, and even using it one time should put you ahead of the game.