Getting random stat boosts?

Question

So I just hatched a new baby Pokemon (porygon) and I ran into a remoraid. I threw a quick ball at it, and it went in. My level one porygon started levelling up a lot, but everytime it levelled up it got random stat boosts. Remoraids are supposed to yield one special attack EV so how was I getting boosts of speed and defence, etc? Does catching a Pokemon change something, or does it have to do with it being level one?

Or am I being totally wrong with how EVs work?

Answer 1

Your Pokemon still has to reach its level 100 base stat total and these stats are added incrementally so it still gains boosts in all of its stats.

EVs are an additional boost on top of base stats, so just because you gained an EV in Sp. Att, doesn't mean you're not going to receive boosts in your other stats when you level.

Answer 2

Being a level 1,the stats it gains are trying to match the stats it will get at later levels while still trying to be a bit even across all the stats.I mean,if you gain only sp.atk EVs,of course you wouldn't get only special attack boosts when you level up.Evs are usually more noticible at later levels.For example, at like level 80,a garchomp EV trained in attack and speed gets like 6+stats for both while getting 3-4+ for other stats
Note that EVs still affect the stats at lower levels,it's just that the effect will be less noticible since you can't get a remoraid at level 5 with 30 special sp.atk with only 15 for the others.

Source:A little bit of common sense and I had read something like this question before