The thing is Meowth kinda can't learn Pay Day because like they said in one episode he used up all his experience in learning how to walk and talk like a human. Also I don't think Meowth would want to learn Pay Day even if he could because he is kinda like more human then pokemon now. He wants to be treated as a human then pokemon so if he does actually take the time to learn how to use Pay Day then it kinda be bad for him. Also he doesn't have time because he is always with Jessie and James make their next new invention and plans.
Also I like Meowth's inventions and they are not always his fault when it blows up. Some times they blow up when Jessie tries to use them like that happens a lots of times. Then there are times when they get over loaded by Pikachu's Thunderbolts or just get destory by Pikachu and Ash's pokemon. Also I like to see what happens if your TV got shocked by a pikachu or some sort of eletrical discharge. I bet it would blow up too. There is no such thing as a perfect invention and Meowth's are no different. I mean if Meowth did made a perfect invention then they would have caught Pikachu by now right and if so there would be no storyline.
