I'm pretty sure it'll evolve after you level it again.
Pachirisu does not evolve :(
Level 30.
level 40
Level 10
level 25
it will evolve at level 21
It will evolve at level 48
Arbok does not evolve
Pachirisu does not evolve :(
If your question implies that you caught a Pokemon that has already passed the minimum evolving level, but has not yet evolved, simply level it one more time, and it should evolve. (However, it CANNOT be level 100 already.)
level them up
At level 10.
level 44
level 26
level 26
Level 24
Level 48.