It's cool, but some of the images look a bit squashed. When resizing images, you should probably try to keep the same aspect ratio.
† I am a Christian and not ashamed of it! Copy and paste this into your sig if you are too.†
Moved this to Digital Media since it's a graphic piece.
Onto the banner, adding to pacman000's comments, I assume the border is black so the random white edges on the right and bottom sides make it look awkward. You can also add more effects too like adjusting the color schemes, adding textures/brushes, etc.
Not bad for a first try. However, as the above poster said, some of the images are kind of compressed and mushy (Chandelure and Mamoswine look uncomfortable). Try to keep the images even, when resizing. Maybe using different images would help you out. Also, as May suggested, don't be afraid to add effects. Experimenting with colours and textures with banners never hurt! Make sure the colours don't clash with one another, or anything like that though. After all, it's the effects (and placement, text, etc) that make the banner; and without it, they wouldn't be as snazzy.
/Best of luck.~
Yeah i only used Word and Paint.
With photoshop i could make it much better.
Thanks for the help
as all of them said, yeah tis a bit squashed but really good for a first try, if ya dont wanna spend money on photoshop you could try GIMP, which is free
Credit to SM