Some Pokémon-ex also have a large amount of HP; cards previously had a limit of 120 HP, but Pokémon-ex ignored this rule and had up to 200 HP. Before the Diamond & Pearl Great Encounters expansion, Wailord ex had the title of the most HP: 200. This was later tied with Wailord in the Great Encounters series and Wailord in the Dragon Blast series.
So, Wailord is the Pokemon with the Highest HP in TCG.
As for attack-wise, it is Rushing Flames, with a max of 4640. However, any card that says Flip a coin and do x damage for the number of y times you get heads/tails can do an infinite amount of damage. Thank trachy for that one.
Source: Pocket Monsters