Why, are you asking , is the verb "Aller" so irregular? Even almost impossible to remember or make sense of?
Well this might help you:
The verb is a combination of 3 latin verbs which used to mean virtually the same thing. There were:
- Allare, réduction of ambulare, gives us the radical we know as well as the subjunctive form.
- Vadere for most the Present indicative as in as in Italian, Spanish, and Portuguese.
- Ire, as in Spanish and Romanian which we use in the future gives us J'irai.
So remember
The form "Allare" gives us
Aller, nous allons, vous allez, je suis allé (+all other forms of the perfect tense), j'allais (+all the forma of the imperfect), que j'aille (+ all the forms of the subjunctive).
The form "Vadere" gives us
Je vais, tu vas, il va, ils vont + the imperative "Va!
The form "Ire" gives us
All the future (j'irai, tu iras, il ira, nous irons, vous irez, ils iront) and the conditionnal (j'irais, tu irais, il irait, nous irions, vous iriez, ils iraient).