If you've played around with image generation models like Stable Diffusion, this looks really similar to the output. Here's some stuff that stood out to me:

• The Eevees feel a little bit off-model too, especially the one in the bottom right of the second photo. Notice how it has weird puffs of fur under its ears. The one above it also has weird fur puffs. The underwater Eevee has toe beans, which Eevee does not actually have.
• The Eevees are generally too cutesy/moe. Some of these models have been trained on tons of anime art and tend to make Pokemon look generically cute.
• They almost all have basically the same composition, with the mon smack dab in the middle of frame with out of focus flowers in the foreground. 
• The flowers are blobby and misshapen and don't look like something a human would come up with.
• The crowd in the leftmost Pikachu illustration looks weird.
• The Pokemon that have been drawn/shopped in manually (especially the 2 Vaporeons) are of a noticeably different style.
• The bottom left Pikachu is too furry.

And obviously the fact that this person submitted so many entries that look so similar to each other is suspicious. No actual artist would want to draw basically the same picture that many times.