what booster packs come in pokemon tins Pokémon TCG: 30th Celebration Product Showcase Pokemon TCG: Poke Ball Tins

The teal and white colouring prominent

At the time of writing, Walking Wake ex, card number 205/162, is valued on TCGPlayer with a market price of $40

If you just want to stomp the game I think things are easiest with Squirtle and friends by far, since you can build it into a Rain Dance deck later and have something that's out of any of the CPU trainers' league, whereas Charizard and Venusaur aren't as competitively powerful(though Pokemon Center cheese with Venusaur is pretty entertaining...), but you can really get away with doing a decent version of whatever you feel like running so I'd just go with whatever you think sounds fun

Given the relatively small additional charge and the extra goodies that you can use for playing the Pokemon TCG with your friends, this is one of the best Mega Evolution products to get started