Okay, some basic tips.
Just about the first gif, for now.
The text is hard to see and read, because it has a light color and lots of whites on an also light and white background (the font is not the luckiest choice either)
The background flashing is not pretty to keep, but annoying enough to lose. It doesn't raise the quality of the gif.
Backgrounds shouldn't have so big differences in colors, especially with so small-print decoration: Yours has black, white, blue, so whatever you put on it, it will not be easy to see. If you put something white on this background, you won't see it because of the white parts, if you put something black on it, it will melt with the black parts and not see those. Unfortunate choice.
The Pokémon pictures. For one, they are too small. More than half of the picture is empty with the background, while the Pokémon are too small to see well. Their size also makes the quality to drop of all of them - you can see how the contours (lineart) disappeared on Celebi, the lack of lineart makes Mew hard to see, the contours party disappeared/pixelated on Victini, makes the details (and the Pokémon overall) hard to see with Jirachi, and Manaphy is just small and doesn't look very good on blue background, being blue herself.
Also, Jirachi and Mew appears to have the white outline from the cutout.
The second picture has awkward color choices, and the girl suffers from low-quality because of the size reduction, while also sporting the unflattering white outline.
The third uses an uncomfortable font, lots of empty spaces, big size with lots of tiny details (strains the eye) and the star of the picture being very small once again. Also, it doesn't seem to have a color theme (like the other pictures) having blue-white-yellow-purple-silver theme with a little limegreen mixed in. It's at least 1-2 colors too much.
The fourth is awful to look at with the flashing stars and text. Choose a font that's easier to read, drop the flashing stars and the glittery text, and make the Pokémon bigger. It's the real star of the picture afterall, no?
At least this time the background is better (no needless details) and the colors complement each other (bright purple for the faded orange of Victini, also matching the eyes) which is very important. But usually the background should pack less color value than the object we should be focusing at, because the eye catches the brighter colors first, which is in case the background (not good).
I hope this helped.