This is Showderp, where someone says they will battle on Pokémon Showdown with a team made up of Pokémon other people suggest. The person who battles is called the champ and the people who suggest are actually Rhyperior.

Here are some links:
memebasemon.com
booru.showderp.com
plug.dj/showderp-1

Current champ:
pizzar !!YSwzfnuy9rU