If youre looking for a quick summary, heres my current tier list for the most popular decks of the format: Tier 1 : Giratina VSTAR, Charizard ex Tier 2 : Mew VMAX, Miraidon ex, Gardevoir ex, Lost Box Tier 3 : Snorlax Stall, Inteleon VMAX / RS Urshifu VMAX, Roaring Moon ex, Iron Valiant ex Please note that this is a summary, not a complete list
There's also a lot of Summoning and Draw Power
Fetchlands like Misty Rainforest are great ways to reset the top of your library to get a fresh look with The Fourth Doctor, but Id also recommend trying out cards like Bant Panorama and Shire Terrace which enter the battlefield untapped and tap for colorless mana in the early-game, and then you can cash in for a basic land and shuffle your library later when you need it
To maximize its utility and reduce the impact of the effects drawback, the player should only activate it in the mid-game at the earliest unless the player already has DON
I think the higher defense power is also good for lower class monsters