Let's pretend OP caught this guy at the bottom of Relic Castle at level 30, it's not unreasonable, given the circumstances, basically Dugtrio from Gen 1. Krokorok is in the Medium slow experience group, so a bit less than 5000 EXP is required to level up each time in that level range. Pokemon are also giving out about 1000 EXP, given level scaling. The only problem is, there aren't that many trainers between the Desert Resort and Elesa's gym, are there? Like, to level up 7 times that's like 30k EXP (a bit of an overestimate maybe), and unless you somehow avoided every trainer in the area or you fought a bunch of higher leveled trainers (or ones with good EXP like the Audino ones in the sports domes). That's still like 10 trainers, which I'm not sure how you scraped together that many (again, aside from visiting the domes). I guess this is like saving Lt. Surge for later in Gen 1, to make another comparison, but less of a curb stomp. I can't even say you've been using the Lucky Egg, that's not until way later.
