Here are the other two paintings:
The shown image in the question contains
The evolutions of all grass starter pokemon from generations 1 through 5:
Bulbasaur,Ivysaur,Venusaur,Chikorita,Bayleef,Meganium,Treecko,Grovyle,Sceptile,Turtwig,Grotle,Torterra,Snivy,Servine,Serperior
because
each row has the color palette of the corresponding pokemon, but treating the RGB value as BGR, which means the shown image doesn't display their "true" colors.
So the other 2 paintings contain
Fire and Water Starters from generation 1-5:
Fire:Charmander,Charmeleon,Charizard,Cyndaquil,Quilava,Typhlosion,Torchic,Combusken,Blaziken,Chimchar,Monferno,Infernape,Tepig,Pignite,Emboar
Water:Squirtle,Wartortle,Blastoise,Totodile,Croconaw,Feraligatr,Mudkip,Marshtomp,Swampert,Piplup,Prinplup,Empoleon,Oshawott,Dewott,Samurott
Story elements:
It's called Evolution because the image portrays pokemon evolutions.
She was going to give me a starter pokemon for the beginning of my journey.
The device is a pokedex.
The assistant professor is probably Bianca, because this story seems to play out in Pokemon Black/White.
Lenora's (gym leader) hometown is Nacrene City, which has a museum and has some vague connection to an ancient festival.
The forest is Pinwheel Forest, right near the city, where she would like to research pokemon!
Not sure about the time and place yet, unlessGen 5 was chosen because it refers tois the factlast generation that in B/W there were 15 starter pokemon of each type going backwas sprite-based, andwith gen 6 switiching to 3d models. And as I said the museum is related to art and has some vague connection to an ancient festival.
Fun Stuff:
(I scraped the color codes from here)
Here are the "unaltered" paintings, i.e. in RGB:
Grass (different horizontal order):
Fire:
Water: