Apologies if it's inappropriate for me to explain in detail, once more, how Mega Alakazam has good reason to win.
Even if it didn't have mind hax, it can just use Miracle Eye to remove immunity to Psychic attacks & then attack Lillie.
Also, it has passive & active healing via Life Force & Recover, respectively, has an alternative means of power copying to Trace via Role Play, & can power null whatever Lille used last with Disable.
Oh & did we mention the literal 5,000 IQ, never forgets anything it learns, performs calculations in battle to gain every edge, the passive mind reading, the danger sensing it would have inherited from being an Abra....
Oh and none of that is from Mega; The Mega reasonably has the previous form's abilities -as Alakazam is highly intelligent, likely remembers previous forms & is a far superior psychic to them- & more.
For example, being able to foresee all of its foe's moves.
Or learning their life from birth to death at a glance.
By the time Lille is thinking "I wanna kill that thing" & deciding to aim, several things have happened:
1.Trace has auto-triggered, per the start of the battle. X-Axis or intangibility likely copied.
2. Since they likely start aware of each other, Mega Alakazam has likely gotten a glance at Lille. Per abilities mentioned above, it has learned Lille's weaknesses and his WHOLE LIFE, plus whatever's in his future, since again, Mega Alakazam learns their life from birth TO DEATH.
3. Mega Alakazam, being superior to base Alakazam, is likely thinking as fast, if not faster than a Supercomputer. Meaning it likely has formulated a plan & evaluated Lille quite thoroughly.
Speed is equalized, yes, but as mentioned earlier in the thread, we don't equalize how fast characters THINK. Reactions, perhaps, but reactions are how fast you physically take action.
Show me something where we have an idiot like Monkey D. Luffy & "world's greatest detective" Batman mentally process information at the same speed; Equalizing thought speed is kind of counter-intuitive to the Intelligence statistic's existence on profiles.
To put it how I see the idea of equalizing thought speed: "You can't be mentally 1 step ahead of your opponent because speed is equalized! There's no way they could plan ahead more or think faster than their opponent!"
Thus, even if Lille DID fire, while it is instantaneous, for all we know, Alakazam has already foreseen the attack coming & planned for it. If it is on target, there's still no guarantee it gets through Alakazam's psychic barriers. Per its durability:
"At least Island level with psychic powers that are always active (Which aren't bypassed by Feint and the like)"
If they aren't bypassed by attacks that bypass Protect & Detect -barrier moves that nullify/block attacks- it's questionable if a barrier bypassing move from someone over 4.3 times weaker than MA will get past.
If they DO get past, Life Force is still passively healing Mega Alakazam, & it can use Disable on The X-Axis & Recover if it survives.
From there, Miracle Eye+Psychic Attack or mind hax.