it would be best if you had some examples pf your work, but ill request one nad see what you some up with.
You say you can do anything, can u do animation? if so....
Banner with Bulbasaur treecko and chikorita
1st have bulbasaur on his own, then treecko on his own, then chiko on his own
then all together.
then Bhikorita on his own fireing vine whip, then treecko on his own doing bullet seed
Then Bulbasaur on hos own, he fires a solar beam which makes a explosion, when the light clears you can see the text
Bulbasaur!
Treecko!
and
Chikorita!
if you cant do animation.....
just a banner with bulbasaur in the middle, treecko on the right, and chiko on the left, text saying
Bulbasuar, Treecko, and Chikorita
fan club
youu decide what looks like the best background.