Could anyone give me an example of a Level 100 EV spread being optimized for Level 50? I've heard before that a Gliscor spread of 248 HP / 248 Def / 12 Spe at Level 50 would be essentially the same as a 252 HP / 252 Def / 4 Spe spread at Level 100, but with one more Speed. And could an explanation be provided? Thanks.
It is possible to follow those suggestions blindly but it does not grant optimal results everytime, especially in pinpoint stats like HP and speed. It's more important to understand why a particularly EV speard is chosen.
Gliscor's Defensive set is actually 244 HP / 248 Def / 16 Spd. Explaination and gripe will be provided.
With 244 EVs in HP Gliscor reaches 352 HP, which is a multiple of eight and should grant the maximum amount of recovery by Poison Heal. In our opinion Gliscor should have 4 more EVs in it because 352 also a multiple of four and just in the case you substitute you will have one less sub to work with; also, should the opponent manage to burn it somehow, you
may get more life out of your Gliscor because burns work with eighths, too.
Anyway, at level 50 Gliscor will heal 22 health at 176 onwards. If you do not use substitue, you cannot go wrong just maximizing the HP. However, if you do plan to use substitue, you must not exceed 179 HP (228 EVs) because at 180 it will generate 45 HP subs, an amount Poison Heal cannot recover in two turns.
The 16 EVs in speed ensures that Gliscor will always outspeed Adamant 252 Scizor; slightly outdated because of Mega-Scizor, but let's pretend it is just a regular SD-Scizor.
At level 50 Scizor reaches a speed of 117. In order to outspeed it Gliscor actually has to have at least 20 EVs in speed.
The equivalent spead for 244 HP / 248 Def /16 Spd at level 100 would be 252 HP / 236 Def / 20 Spd at level 50.
The equivalent spead for 248 HP / 244 Def /16 Spd at level 100 would be 228 HP / 4 Atk / 252 Def / 4 SDef / 20 Spd at level 50 - yeah, it looks weird. Just play with the Pokemon Showdown sliders a bit and you will understand.