When in the turn
The simulator orders each turn in phases. Switches go first, then Mega Evolutions and then moves, by priority and Speed. Last come end-of-turn effects, such as sandstorm damage.
That has two practical consequences. A Pokémon Mega Evolves even if it uses Protect that turn, so Mega plus Protect on turn one gives you the weather and the new stats without risking anything while you see what the opponent does. And Fake Out does not stop Mega Evolution: when it lands, the Pokémon is already a Mega, even if it flinches and does not attack.
If Pokémon on both sides Mega Evolve, they do so in Speed order, and that decides which weather stays when two weather Megas face each other.
| Turn phase | What happens |
|---|---|
| 1 | Pokémon switches |
| 2 | Mega Evolutions, in Speed order |
| 3 | Moves, by priority and Speed |
| 4 | End-of-turn effects |
The new Speed counts from turn one
In Champions, after each action the simulator recalculates everyone's Speed and reorders the remaining moves. Since Mega Evolution is an action, the Mega attacks that same turn with its new Speed. It was not always like this: in Pokémon X and Y the pre-Mega Speed was used, and in Sun and Moon only the Pokémon's own Speed was recalculated.
For some Megas the change is huge. Mega Garchomp Z goes from 102 to 151 base Speed, and with full Speed investment it rises from 169 to 223 before attacking. The same rule applies to any Speed change in the middle of a turn: if an opponent lowers yours before you move, you already move with the new one.
| Pokémon | Base before | Mega base | Maximum before | Mega maximum |
|---|---|---|---|---|
| Garchomp (Mega Z) | 102 | 151 | 169 | 223 |
| Salamence | 100 | 120 | 167 | 189 |
| Froslass | 110 | 120 | 178 | 189 |
| Tyranitar | 61 | 71 | 124 | 135 |
| Charizard (Mega Y) | 100 | 100 | 167 | 167 |
The switch-in ability and the Mega ability
A Pokémon enters battle with its regular ability and swaps it for its Mega's on Mega Evolving. If the Mega's ability works on entry, like Drought, Snow Warning or Sand Stream, it activates at that moment. That is why Mega Garchomp Z, with Levitate, is already immune to Ground-type attacks on the turn it Mega Evolves.
The regular ability is not entirely lost: if it works on switch-in, it does so before Mega Evolving. Salamence comes in with Intimidate, lowers the opponents' Attack and then Mega Evolves and gets Aerilate. The opposite happens with Tyranitar: it sets sand on switch-in and, when it Mega Evolves, Sand Stream does not renew it, because setting the same weather again does not extend it.
One per battle and a stone that is never lost
You can bring several Mega Stones on your team, but only one Pokémon Mega Evolves in each battle: as soon as one does, the others lose the option. The Mega lasts the whole battle, even if the Pokémon switches out; if it comes back in, it does so as a Mega and its ability activates again on entry.
The Mega Stone cannot be removed from its Pokémon. Knock Off does not knock it off and, since it cannot remove it, it does not get the 50% power boost it has against a target holding an item either. Trick and Switcheroo fail. So against a Mega, do not count on taking its item.
When to wait before Mega Evolving
It is almost always worth Mega Evolving as soon as the Mega comes in: the new stats, ability and Speed count from that turn. But there are cases where waiting makes sense, and this is our own reading.
If you bring two Megas, Mega Evolving the one that comes in first closes the door on the other; if team preview tells you the right one is in the back, save the Mega for it. And with Salamence, every time it comes in without Mega Evolving it uses Intimidate again: if your plan is to switch it several times to lower the opponents' Attack, the Mega can wait.
