EV training, is it worth it?

Ok, so I've been a pokemon nerd ever since I was 5, and starting with Diamond I've bought one version of each generation to date (including Platinum). So I REALLY want to enter the National Championships someday, but my main team consists of 5 grass pokemon (each starter from each region, legitimately obtained, no AR for me) and my shiny Absol (also legitimate). But I don't dare try to enter that team, because any trainer who knows type match-ups will send out a Bug type an flatten me. What I'm trying to do is create a nice balanced team to face nearly every challenge. And I have most of the members selected, but I need an outside opinion here; should I EV train them?

I know what EV training is, and I have EV trained quite a few pokemon, most notably my February event Mewtwo, who has a special attack stat of 406 (no, I'm not lying). But all his other stats (aside from speed, the other stat I maxed, somewhere in the high 300's range) are really kind of bad. Because I put all those EV's into Speed and Special attack, his defense and special defense are very low, and any strong hit will wipe him out (his main defense is hitting first and not being hit, which works fine until my brother pulls out his Arceus).

So should I EV train my Nationals team and max out 2 stats, or should I just level them up the old fashioned way (any trainer willing to fight me) and let them get fairly balanced stats?

Don't not care about EV's like that. I reccomend trying to breed good IV's and EV train from the start. You can just do the classic switch-out-and-train method. Any battle you earn EXP will earn you EV's. Also you don't need to max out 2 stats. I know people who use very abstract EV's like Conkeldurr having one extra speed just to outspeed every other normal set conkeldurr.

I reccomend checking the Smogon OU/Uber tier list (Uber because they have their tiers based on their Pokemon Online server)

Also Mewtwo can die easily to Arceus because Mewtwos base stats are 680 whereas Arceus's are 720.

If you need help reccomending pokemon and sets just send me a messege (I will reccomend using a Sunshine team because Drought Ninetales and a Chlorophyll Jumpluff along with some other pokemon that can balance things out)

I did not know that about Arceus. That makes me feel a little better XD Now I'll go EV train my Arceus, too!

I totally failed to take abilities into account D: Oops. Trainer Fail Moment.

I think I will go look at that website. I wanted to do Nationals as sort of a half-thought-through kind of decision, but I think it's clear that I need to do my homework XD Otherwise, I will be squished. Like a Weedle.

If you're thinking about entering a competitive tournament a lot then it's best to EV train them. That extra point may be the one to save you and win you the match. And with others EV and IV training, it's good to get an upper edge.

EV training is good, I trained a pocchyena on lv 10 (freshly caught) and got its attack to 26 only moving up 2 lvs! Then I accidently turned off the power without saving ):