Caterpie evolves into Metapod at level 7, and then into Butterfree at level 10
Bellsprout evolves into a Weepinbell at level 21 in Pokemon Crystal.
It evolves at Lvl. 25
If you ever get an eevee, you level it up there and it evolves into glacion. There is no rare pokemon inside.
Quilarva is not a pokemon, you might be thinking of Quilava, which is in Pokemon (heart) Gold, (soul) Silver, and Crystal. It evolves into Typhlosion at Lv.36.
Caterpie evolves into Metapod at level 7, and then into Butterfree at level 10
Natu evolves at level 25.
Cubone evolves at level 28
In Pokemon Crystal, Totodile evolves into Croconaw at level 18, then evolves into Feraligatr at level 30; Chikorita evolves into Bayleaf at level 16, and then Meganium at level 32; and Cyndaquil evols into Quilava at level 14, and then Typhlosion at level 36.
Bellsprout evolves into a Weepinbell at level 21 in Pokemon Crystal.
Pidgey evolves into Pigeottoat level 18. Pigeotto evolves into Pidgeot at level 36.
Eevee evolves in to a glacé on by training it by one level then it will evolve
It evolves through happiness
it evolves with a leaf stone
Totodile evolves into Croconaw at level 16.
Spinarak evolves at level 22 in to an ariados.
Bellsprout evolves into Weepinbel at level 21.