The other answer doesn’t really give details on actually EV training your Pokémon, so here’re some good EV hotspots in HGSS.
And here’s a basic guide to EV training in general, although I believe you’ve asked an EV question before, so you should already be familiar with this.
Although if you want to train your ingame team, then they’re going to have some EVs already, and some of them could even be maxed. sumwun’s suggestion of overlevelling and using super effective attacks is likely going to get you better results against Lance than EV training. I just wanted to give some resources in case this question comes up on Google.
