Pokemon XY

you will like this anime if you like the yu-gi-oh! franchise They are also both action,adventure animes 

The color scheme/ atheistic is very similar and I think both anime encapsulate childhood wonder and innocence pretty well. They have well executed fights that are interesting to watch. Gon and Ash have similar approaches to fights and situations of danger. Gon and Ash are also very stupid. 

The stupid main character and his/her slightly-less-stupid friends go on many crazy adventures. Both involve talking animals. They are both funny, colorful, and very enjoyable! 

Both main characters have the same goal: become the best of their worlds. While in Pokemon they travel in the lands, challenging people and dealing with the bad guys, in One Piece they travel in the sea, dealing with the bad guys and the ones that should be considered the "good guys". Both animes are slow, but will give you a weekly dose of entertainment 

"Gotta get/collect them all" theme and "monster of the week" themes. However it should be noted that monster battles are more action-packed and intense in Pokemon, while Monster summons in Youkai watch have less action and usually depend more on the Youkai's special abilities (e.g. possession).