Let's analyze the new rules, shall we?
- Attacks that require no Energy
Some people say this will break the game. I disagree as it reduces luck factor as what if you do not have any energy in hand and won't get any for a long time. At least, energy-less attacks can give you not so much of a disadvantage if the opponent is faster.
- The player going first can't play any Trainer Cards (Trainers, Supporters, or Stadiums) on their initial turn.
In Modified, it stops t1 rare candy,cessation crystals, etc. but otherwise IMO no so much different than the original "no supporters first turn." The impact on Unlimited is probably going to be huge though.
- Claw Fossil, Mysterious Fossil, and Root Fossil can not be put into play on the first player's initial turn. These cards CAN be put into play during the initial setup phase.
Superb. No more annoyance of putting down the fossil if the fossil is the only basic in hand. However...
- If Claw Fossil, Mysterious Fossil, or Root Fossil is Knocked Out, the opponent takes a prize.
Okay, this killed the uniqueness of fossils and reduced the usability of fossil Pokemon. As if they were not restricting enough, now we have no compensation getting them to the field. No more stall decks like Polistall (as frustrating as they are, stalling is a legal strategy and time limit already deter making stall decks)... They are now just extremely inferior basics.
- Trainers, Supporters, and Stadiums are all classified as "Trainer Cards," but only Trainers, Pokemon Tools, and Technical Machines are considered "Trainers".
So far, this rule hasn't affected anything. Maybe in the future, they make a "Trainers" lock power, kinda like Dark Vileplume, but doesn't stop supporters or stadiums.
- Weakness and Resistance are now customized to each Pokemon. When calculating Weakness and Resistance, add or subtract the number written in the Weakness and Resistance section of the card.
I quite like this rule. Weakness is no longer as dangerous as before but still play a big role. OHKO will be less common, which is a good thing.
- Basic Energy versions of Darkness and Metal energy.
Unless they make special versions of the other basic energies, Dark and Steel Pokemon just got a BIG boost. Now, they have a basic, which much easier to search and recover, while the special gives them additional power/defense, which is not available to the Pokemon of other types. Let's not forget NG Sneasal...
- Leveling Up Pokemon/LV. X
It's a new twist of getting Pokemon out so it's gets some points for originality. LV. X is a nice mix between ex and * Pokemon. No more 4 ex and 4 normal. Now you have something like 2 normal and 2 LV. X, and no more risk of your opponent drawing 2 prizes. You also lose absolutely nothing when you level up (you get to keep previous attacks and powers!) I'm quite interested to see how this would affect Unlimited, as the early Pokemon had levels on them as well, maybe creating new combos...
So summarizing...
The Good:
Attacks that require no Energy
No more fossil as only basics
Customized Weakness/Resistance
Leveling
The Bad:
Fossils counting as Prizes
Basic Darkness/Metal
No "Significant" effect:
Trainers Categorization
No First-Turn Trainer Cards
The new rule's goods seem to outweigh the bad, but we'll have to see it in the metagame to actually determine if these changes are healthy or not.